Definitions:　

アイする = "to love"
しあう = -i au form = "to _ each other"
二人 = "two people"
が marks the subject
トーダイ = 東京大学(とうきょうだいがく) = Tokyo University
って marks a quotation
とこ = ところ = "place"
には marks a location
いる = "to be"
と = "if/when"
ね requests the other person's attention or acknowledgement

Definitions:　

大きい = "big"
く = adverb form
なる = "to be"/"to become"
　大きくなる = "to become large" = "to grow up"/"to become adults"
ったら = -tara form = "if"/"when"
ふたり = "two people"
で marks a means, corresponds to "with"
いっしょに = "together"
トーダイ = 東京大学(とうきょうだいがく) = Tokyo University
行く = "to go"
こう = volitional form
ね requests the other person's attention or acknowledgement

Definitions:　

大人 = "adult"
になる = "to become"
ったら = -tara form = "if"/"when"
絶対 = "definitely"/"without fail"
トーダイ = 東京大学(とうきょうだいがく) = Tokyo University
で marks a situation, corresponds to "at"
会う = "to meet"
おう = volitional form
ね requests the other person's attention or acknowledgement

Definitions:　

そういう = "that sort of"
ワケ = "reason"/"circumstances"
で marks a situation, corresponds to "with"
とりあえず = "for now"/"at the moment"
２浪 = ２度浪人 = two-time rounin = someone who failed his college entrance exams two years in a row
する = "to do", in this case "to do _ for a living"/"to be a _"
してる = -teru form = "_ing"/present tense
ます = polite form

Definitions:　

東大 = Tokyo U
のみ = "only"/"just"
を marks object
受ける = "to accept", in this case "to take (a test)"
受けつづける = compound verb, "to continue taking (a test)"
つづけ = -i form, in this case conjunctive
落ちる = "to fall", in this case "to fail (a test)"
落ちつづける = compound verb, "to continue failing (a test)"
つづけて = -te form, in this case conjunctive
３年目ー = "3rd year"
Notice there is no verb following the conjunctive -te. We assume an implied verb at the end. It must be past tense since multiple years' worth of exams can't all take place in the present. になった is the obvious candidate.

Literal Translation:	I continued taking tests and failing tests at only Tokyo U and it became third year.
Adapted Translation:	For two years I've only taken (and only failed) Tokyo U's entrance exam, so now it's my third year as a rounin.

Definitions:　

とうとう = "finally"
家 = "house"
を marks an object
追い出す = compound verb, "to chase out"
される = passive form ("to be chased out")
た = past form ("was chased out")
俺 = "I"
は marks subject
その = "that"
温泉 = "hot spring"
街 = "street"/"neighborhood"/"area"/"town"
へ marks a destination
やってくる = "to come/arrive somewhere"
きた = past form, "came/arrived somewhere"

Definitions:　

たしか = "certain"/"sure", often best translated with "I was sure that..."
この = "this"
辺 = "area"/"surroundings"
だった = past form of だ, equivalent to "was" in a verbless sentence
はず = "should", as in "likely"/"probably"/"supposed to be"
だけど = "but", "however", "although"

Definitions:　

ここ = "here"/"this place"
が marks a subject
婆ちゃん = "grandma"
が marks subject
経営する = "to manage (a business)"
してる = -te iru form, "managing (a business)"
旅館 = "hotel"/"inn"

Definitions:　

ちょっと = "a little"
事情 = "circumstances"
が marks a subject
ある = "to be"
ります = polite form
して = conjunctive -te form
受験勉強 = "studying for an exam"
が marks a subject
する = "to do"
したい = -i tai form
で is a transition
しばらく = "for a while"
泊める = "to let someone stay (temporarily live) somewhere". Note that 泊まる = "to stay (temporarily live) somewhere".
てもらう = -te morau form, "to have someone let someone stay somewhere"
えません = negative polite form, in this case a rhetorical negative (note that, in English, a rhetorical negative is inappropriate when you're trying to be polite)
か marks a question

Literal Translation:	There are a little circumstances, and I want to study for an exam, so couldn't you let me stay a while?
Adapted Translation:	Some stuff happened, and I need somewhere to study for my exams, so could I stay here for a while?

Definitions:　

あれ normally means "that", but in this case it's an interjection equivalent to "huh?"
婆ちゃん = "grandma"
も marks one of multiple subjects
旅館 = "hotel"/"inn"
の = "of"
人 = "person"/"people"
も marks one of multiple subjects
留守 = "(state of being) absent/away from home"
かな marks a question

Definitions:　

この = "this"
物語 = "story"/"tale"
は marks a subject
フィクション = "fiction"
です is a polite gobi
実在 = a word for "reality" used in formal contexts
の = "of"
人物 = a word for "person" used in formal contexts
団体 = "group"
名 = "name"
等 = など = "_ and the like"/"things such as _"/"etc."
とは = in this case the と is like "with"
関係 = "relationship"
ある = "to be"
りません = polite negative form

Literal Translation:	This story is fiction. There is no relation to any names of actual persons or groups.
Adapted Translation:	This story is fictional. Any resemblance to names of actual persons or groups is entirely coincidental.

Definitions:　

ここ = "here"/"this place"
で marks a situation, corresponds to "in"
待つ = "to wait"
待たせてもらう = -asete morau form, combination of causative and -te morau forms (see CV entry)
か marks a question

Definitions:　

全く = in this case, an interjection like "geez", "come on", "seriously"
うち = "my family"
の = "of"
バカ = "idiot"/"stupid"
親 = "parent(s)"
と marks an object
くる = "to come"
きたら = -tara form = "if"/"when"
　ときたら = "when it comes to"
息子 = "son"
を marks object
バカ = "idiot"/"stupid"
扱い = "treatment"/"handling"
する = "to do"
　バカ扱いする = "to treat someone like an idiot"
しやがる = -i yagaru form, expresses anger
って = -te form, in this case I think it's acting as a loose transition into the next line

Literal Translation:	Geez, when it comes to my stupid parents, they treat the son like an idiot (which I am angry about).
Adapted Translation:	Geez, do my stupid parents really have to treat me, their own son, like such an idiot?

Definitions:　

何 = "what?"
が marks subject
地球 = "Earth"
が marks subject
滅亡する = "to be destroyed/ruined"
しても = -temo form, "even if _ is destroyed/ruined"
お前 = "you"
は marks subject
東大 = Tokyo U
なんて = in this case, "_ and such", i.e. "a university such as Tokyo U"
入る = "to enter"
れる = potential form, "to be able to enter"
ない = negative form, "to be unable to enter"
だ is a gobi
失礼する = "to be rude/impolite"
してしまう = -te shimau form = "regrettably"
ちゃう = shortening of -te shimau form
ぜ adds masculine emphasis

Literal Translation:	What is "Even if the Earth is destroyed you will be unable to enter a place such as Tokyo U"? That is (regrettably) rude.
Adapted Translation:	Why'd they have to say "You'll never get into Tokyo U even if hell freezes over"? That's just rude.

Definitions:　

確か = "definite"/"sure"
に marks the previous word as an adverb, "definitely"/"surely"
俺 = "I"
は marks a subject
偏差値 = "_th percentile"
48 = 48
で marks a situation
英語 = "English"
も marks one of multiple subjects
ダメ = "useless"/"hopeless"/"no good"

Definitions:　

数学 = "mathematics"
現国 = 現代国語 = "modern national language" = "Japanese (as a school subject)"
日本史 = "Japanese history"
生物 = 生物学 = "biology"
all of the も's mark one of multiple subjects
全く = "really"/"completely"/"entirely"
ダメ = "useless"/"hopeless"/"no good"
だけど = "but", "however", "although"

Definitions:　

考える = "to think"
てみる = -te miru form, "to try thinking"/"to think and see what happens"
れば = hypothetical form, "if I try thinking"
勉強 = "studies"
だけ = "only"/"just"
じゃない = "not"
じゃなく = じゃなくて = conjunctive -te form
スポーツ = "sports"
all the も's mark one of multiple subjects
ダメ = "useless"/"hopeless"/"no good"
顔 = "face"
パッとしない is a way of expressing vague dissatisfaction with something. It may help to interpret パッとする as meaning "to immediately hit upon a reason why something is good".
し is a particle that acts like conjunctive -te on non-verbs
とりえ = "positive trait"
ない = "none"

Literal Translation:	If I try thinking about it, not only studies, but sports also hopeless, face vaguely unsatisfactory and no positive trait.
Adapted Translation:	Now that I think about it, it's not just my studies. I'm also terrible at sports, my face doesn't look great, and there's nothing else good about me.

Definitions:　

ほんっと = ほんとう = "truly"/"really"
モテる = "to be popular with the opposite sex"
要素 = "element"
が marks subject
全然 = "completely"
ない = "none"
男 = "man"
われながら = literally "while me", a phrase the speaker can use to indicate their emotional response to something they themselves did. It may adapt to "if I do say so myself" or "I can't believe I did/I'm so", or may simply be dropped in translation.

Definitions:　

一度 = "one time"
で marks a situation. In this case, the hypothetical situation in which he dates a girl only once.
いい = "good"/"fine"/"OK"
から = "so"/"because"/"from"/"since"/"starting from _"
女の子 = "girl"
と = "with"
デート = "date" (as in going on a date, as opposed to a calendar date)
する = "to do"
したい = -i tai form

Definitions:　

いや = as a transition or lead-in, "no"/"well"/"actually"
この = "this"
際 = "situation/circumstances (at a particular time)"
お話する = "to talk (with someone)"
できる = potential form
だけ = "only"/"just"
でも = "even", "but" or "something like"
いい = "good"/"fine"/"OK"

Definitions:　

何せ is the same as どうせ, but much less common. See CV entry.
この = "this"
20年 = "twenty years"
の = "of"
俺 = "I"
の = possession
人生 = "life" (as in "someone's life", not "life vs death" or "sentient life")

Definitions:　

小中高 probably means "小学, 中学 and 高校" = "elementary, middle and high school"
と = "if/when"
女子 = "girl"
には = "in the case of"
避ける = "to avoid"
られる = passive form, "to be avoided"
られ = conjunctive -i form
バカ = "idiot"/"stupid"
にする = "to make into _"/"to make it the case that _"/"to decide on doing _"
　バカにする = "to make fun of someone", literally "to make someone into an idiot"
される = passive form, "to be made fun of"
され = conjunctive -i form
体育祭 = "athletic festival"
でも = "even", "but" or "something like"
出番 = "turn (to do something)"/"chance (to contribute/appear on stage)"
が marks a subject
ない = "none"
くて = -te form, in this case leads into the next line
Since the verbs are all conjunctive (and the next line is verbless), we have to assume an implied tense. Since he's taking college entrance exams, it's pretty obvious that events from elementary/middle/high school should be in past tense.

Literal Translation:	When (I was in) elementary, middle and high school, I was avoided and made fun of by girls, and even at the athletic festival(s) I had no turn.
Adapted Translation:	Girls avoided and made fun of me throughout elementary, middle and high school. Even during athletic festivals, I never got to do anything.

Definitions:　

おまけ = "an extra"
おまけに = "in addition"
趣味 = "hobby", "tastes"/"preferences"
の connects a noun phrase to the noun it describes
プリクラ = "photo booth stickers"
集め = gerund of 集める "to collect"/"to gather" = "collection"
は marks a context
全部 = "all"/"everything"
ひとり = "one person", "alone"
で marks a means
うつる = "to appear/be in (an image or video)"
ってる = -te iru form = "_ing"/present tense

Literal Translation:	In addition, (in the context of) my hobby photo booth sticker collection, I am appearing in everything alone.
Adapted Translation:	Not only that, but all the photo booth stickers I collect are just pictures of me, all by myself.

Definitions:　

ダメ = "useless"/"hopeless"/"no good"
やっぱ = やっぱり = "as I thought"/"indeed"/"after all"
何としても = "no matter what", literally "even if I do 'what?'"
東大 = Tokyo U
に marks a location
入る = "to enter"
って = conjunctive -te form
ハクをつける = "to give something dignity", literally "to attach (e.g., gold) foil/leaf to something"/"to gild something"
ない = negative form
と = "if/when"
Note that ないと almost always has a modal implication.

Literal Translation:	Aaaaaaah! No good, no good, after all no matter what I have to enter Tokyo U and give myself dignity.
Adapted Translation:	Aaaaaaah! Dammit, dammit, I really do need to get into Tokyo U and get my dignity back.

Definitions:　

この = "this"
まま = "state of being"/"tendency of progression"/"what's happening"
じゃ = では = "given _"/"in the case of _"
　このままじゃ = "at this rate"/"given that this is what's happening"
一生 = "whole life"/"lifetime"
彼女 = "girlfriend"
も marks one of multiple subjects
できる = "to be able to do something" or "to get/make something"
ない = negative form

Definitions:　

今頃 = "around now"/"these days"
あの = "that"
思い出 = "memory"
の = "of"
彼女 = "she"
は marks subject
どう = "how?"
する = "to do"
してる = -te iru form = "_ing"/present tense
かな marks a question

Definitions:　

今 = "now"
じゃ = では = "given _"/"in the case of _"
名前 = "name", sometimes specifies "given name"/"first name"
も marks one of multiple subjects
顔 = "face"
も marks one of multiple subjects
うろおぼえ = "faint memory"

Definitions:　

モテる = "to be popular with the opposite sex"
た = past form ("was popular with the opposite sex")
のは marks a clause ("was popular") as the context
あの = "that"
一回 = "one time"
だけ = "only"/"just"
だった = past form of だ, equivalent to "was" in a verbless sentence

Definitions:　

しかし = "however"/"still"/"but"
婆ちゃん = "grandma"
の marks possession
旅館 = "hotel"/"inn"
が marks a subject
こんな = "this" (strictly an adjective, e.g. "this good" not "this is good")
立派 = "splendid"
だった = past form of だ, equivalent to "was" in a verbless sentence
とは marks a subject that could be interpreted as a quote
Actually interpreting it as a quote is most easily done by assuming the implied verb is 思わなかった "didn't think".
ラッキー = the English word "lucky", which in Japanese is often used as an interjection like "Yes!" or "Yay!"

Definitions:　

よぉ～～～し！ = よし = いい = "good"/"fine"/"OK", but よし is often used as an interjection like "OK!"/"Yes!"/"Yeah!"
悩む = "to worry"/"to think hard"
んでる = -teru form = "_ing"/present tense
ても = -temo form = "even if _", often equivalent to one of English's "-ever" pronouns
しょう = 仕様 = "way"/"method"/"solution"
が marks a subject
ない = "none"
しょうがない is a common phrase literally meaning "There is no solution/way (of dealing with it)" and often equivalent to "there's no choice" or "it can't be helped".

Definitions:　

やっぱ = やっぱり = "as I thought"/"indeed"/"after all"
昼 = "daytime"/"midday"/"lunch"
ぶろ = 風呂（ふろ） = "bath"
は marks a subject
サイコー = 最高 = "highest"/"best"
よね requests the other person's attention or acknowledgement
ゴク楽 = 極楽 = "paradise"

Definitions:　

ねぇねぇ requests the other person's attention. This is essentially the gobi ね being used as an interjection.
聞く = "to hear/listen" or "to ask"
いて = -te form, in this case a soft command since nothing modifies it further.
私 = "I"

Definitions:　

最近 = "recently"/"lately"
ムネ = "chest"
大きい = "big"/"large"
く = adverb form
なる = "to be"/"to become"
った = past form, "was"/"became"
と marks a quote-like object
思う = "to think"/"to feel"
わない = negative form

Definitions:　

まぁ = "well"
あんた = "you"
には marks a context and an object
まだ = "still" or "not yet"
全然 = "entirely"/"completely" or "not at all"
かなう = 敵う = "to match up to"/"to be as good as"
わない = negative form
けど = "but"/"however"/"although"

Literal Translation:	Well, (mine) do not match up to you at all though.
Adapted Translation:	Well, they're still nothing compared to yours though.
Since Keitarou obviously doesn't have boobs for her to compare against, this line tells us that she's mistaking him for some unknown female character.

Definitions:　

それっ normally means "that", but it's also an interjection normally used when making some kind of attack.
もむ = "to rub"/"to stroke"/"to fondle"
んでしまう = -te shimau form = "to finish _ing", often the intent is something like "get it over with" or "just do it already"
じゃう = -chau form = shortening of -te shimau form
え = command form

Definitions:　

あれ normally means "that", but in this case it's an interjection equivalent to "huh?"
何 = "what?"
この = "this"
固い = "hard"/"stiff"
の in this case is short for もの meaning "thing"/"person"

Definitions:　

なんか = "something"/"somehow"/"for some reason"
だんだん = "gradually"
大きい = "big"
く = adverb form
If she had finished her sentence, the verb would almost certainly be なってる, meaning "being"/"becoming".

Definitions:　

そう in addition to meaning "that", is often used like "I see"/"is that so?"/"that is so"
か marks a question
俺 = "I"
まちがえる = "to be mistaken"/"to make a mistake"
て = conjunctive -te form
女湯 = "women's bath"
に marks a location
入る = "to enter"
ってしまう = -te shimau form = "regrettably"
ちゃう = shortening of -te shimau form
った = past form
かも = "maybe"/"might"/"possibly"

Definitions:　

何 = "what?"
や = Kansai-ben for だ
あんさん = Kansai-ben shortening for あんたさん = "you"
見かける = "to happen to see"/"to notice"
ん = shortened negative form
顔 = "face"
やな = Kansai-ben for だな

Literal Translation:	What? You are not a face I happen to see.
Adapted Translation:	Huh? I haven't seen you here before.
Since these translations need to match the literal meaning in order to be of any use to students, and that restricts how much I can adapt them, I won't attempt to incorporate any Kansai-ben into the translations.

Definitions:　

なんで = "why?"
次 = "next"
から = = "so"/"because"/"from"/"since"/"starting from _"
へと = "toward"
次から次へと is literally "from the next to the next" (I assume the two "next"s are meant to refer to the first and second next thing) and is roughly equivalent to "one after the other".
女の子 = "girl"
が marks a subject
The implied verb here is almost certainly 出てくる meaning "to come out".

Definitions:　

モォ = もう is an interjection expressing dissatisfaction or annoyance, but not necessarily anger.
何 = "what?"
の connects a noun phrase to the noun it describes
騒ぎ = -i form/gerund of 騒ぐ = "uproar"/"noise"/"fuss"
ですか marks a question with added formality

Definitions:　

違う = "to be wrong/inaccurate"/"to be different"
わよ is a distinctly feminine gobi
あいつ = "he"/"that"
チカン = "pervert", often specifies someone who attempts to touch or fondle women, rather than a mere vouyer or peeping tom.

Definitions:　

チカン = "pervert", often specifies someone who attempts to touch or fondle women, rather than a mere vouyer or peeping tom.
だと, when used to end a sentence like this, means the implied part of the sentence is 言うのか. Thus the と is marking the quote-like object of 言う ("to say"), だ is part of the quotation itself and the か at the end marks this as a question.

Definitions:　

あっち = "that way"
や = Kansai-ben for だ
露出狂 = 露出 "exposure" + 狂う "to go insane" = "exhibitionist"
やて = Kansai-ben for だって, which in this case acts like an emphatic version of だ since she's not quoting anyone else

Definitions:　

フル = the English word "full"
チン = チンポ = crude word for "penis", roughly equivalent to "dick"
丸出し = state of being "exposed"/"bare"
やて = Kansai-ben for だって, which in this case acts like an emphatic version of だ since she's not quoting anyone else

Definitions:　

しまう = "to end/finish"
った = past form
As you may already know, the -te shimau form is often used to express that an action is regrettable. Likewise, しまった by itself is used as if it meant "I did something regrettable", i.e. "I screwed up" or simply "Crap!".

Definitions:　

ちょっと = "a little (of something)"/"a short while"
待つ = "to wait"
て = soft command -te form
よ adds emphasis
俺 = "I"
は marks a subject
ただ = "only"/"just"/"merely"
婆ちゃん = "grandma"
を marks an object
訪ねる = "to visit (someone)", note that with other kanji (尋ねる or 訊ねる) this means "to ask/enquire"
て = conjunctive -te form
くる = "to come"
きた = past form
だけ = "only"/"just"
で marks the situation and/or acts as a transition like "so"

Definitions:　

ただ = "only"/"just"/"merely"
その normally means "that", here it's a (space filler) interjection
この = "this"
旅館 = "hotel"/"inn"
に marks a location
ちょっと = "a little (of something)"/"a short while"
泊める = "to let someone stay (temporarily live) somewhere". Note that 泊まる = "to stay (temporarily live) somewhere".
てもらう = -te morau form, "to have someone let someone live/stay somewhere"
おう = volitional form
と marks a quote-like object
The と very heavy implies a verb like 思う ("to think"/"to feel").

Definitions:　

別に = "not particularly/especially" when the main verb is negative
のぞく = "to look in"/"to peep"
もむ = "to rub"/"to stroke"/"to fondle"
見せる = "to show" (in this line he's referring to when he accidentally showed one of the girls his penis on the previous page)
たり and だり = -tari form
する = "to do"
つもり = "intention"/"plan"
は marks a subject
The implied verb is probably something like ありませんでした = formal past negative form of ある ("to be")

Definitions:　

旅館 = "hotel"/"inn"
に marks a location
泊まる = "to stay (temporarily live) somewhere". Note that 泊める = "to let someone stay (temporarily live) somewhere".
ですって = a more formal だって, which marks a quotation. Like the やてs earlier, she isn't actually quoting anyone, but this time she is paraphrasing what Keitarou said, so the literal interpretation is now "you say" instead of the default "I say".

Definitions:　

この = "this"
期 = "time", usually a period of time that can be precisely defined (e.g. a school term).
に marks a figurative location
及ぶ = "to go as far as"/"to amount to"/"to reach/equal/match something"
んで = conjunctive -te form
The phrase この期を及んで literally means "to reach this time and...", and its usage/intent is similar to "after all this time" in that it implies the passage of time has caused some action to no longer be a good idea.
よい = いい = "good"/"fine"/"OK". Note that いい is very strange in that it always changes to よい before doing any conjugation.
く = adverb form
　よく = "well" or "often". The "well" meaning can end up being very close to "impressively", and with this meaning よく can even be used to express anger, in which case its usage is similar to "I can't believe you'd _" or "how dare you _".
そんな = "that"/"that sort of"
ウソ = "lie"
が marks a subject
つく = literally "to attach"
For some reason, うそをつく means "to tell a lie".
ける = potential form

Definitions:　

ここ = "here"/"this place"
が marks subject
旅館 = "hotel"/"inn"
だった = past form of だ, equivalent to "was" in a verbless sentence
のは marks the whole previous clause as the context, often means "that which is _" or "the fact that _"
もーーー = もう = "already"/"no longer"
ずっと = "the whole time" or "for a long time"
前 = "before"/"previous"
の = "of"
話 = "conversation"/"story"/"topic"/"issue"

Definitions:　

男子 = slightly formal word for "boys"/"men"
禁制 = "prohibition"/"ban"
の connects a noun phrase to the noun it describes
契約 = "contract"
アパート = アパートメント = the English word "apartment"

Definitions:　

さぁ as a transitionary interjection is close to "now then"
おとなしい = "obedient"/"quiet", the precise intent is often "not causing trouble"
く = adverb form
警察 = "police"
に marks a location
行く = "to go"
ってもらう = -te morau form, "to have someone go"

Literal Translation:	Now then, (we) will have you go to the police obediently.
Adapted Translation:	Now we're going to turn you into the police without any more trouble.
Note that we can tell Naru (the girl speaking on the previous page) says this line because she's the only character present who consistently uses feminine gobi like わよ.

Definitions:　

うち = "I"
In Kansai-ben, うち can be used just like あたし or any other first-person pronoun. In Kantou-ben, if うち is used as a first-person pronoun, it's more likely to mean "we" as in "me and my family" (since うち means "house"). Arguably, both uses are in effect here.
の marks possession
寮 = "dormitory"/"hostel"
に marks a location
忍びこむ is a compound verb using 忍ぶ ("to hide"/"to sneak") and 込む. As is the norm with compound verbs, the 込む is equivalent to "into".
なんて in this case resembles とか in that it means "such a thing as _"
ええ = Kansai-ben for いい = "good"/"fine"/"OK"
度胸 = "nerves"/"guts"
する = "to do", in this case the usage is slightly colloquial and more like the English verb "to have"
しておる = -te oru form, Kansai-ben for the -te iru form
しとる = -toru form, Kansai-ben for the -teru form
ホンマ = Kansai-ben for ほんとう = "truly"/"really"

Literal Translation:	Such a thing as sneaking into my dorm, you're having good nerves, really.
Adapted Translation:	You have some real nerve, sneaking into our dorm like that.
Likewise, the Kansai-ben makes it obvious that either Kitsune or Kaolla (the two female characters shown on page 21) is the one saying this line. Since Kaolla tends to use simple, childish language, it's almost certainly Kitsune.

Definitions:　

寮長 = "dorm manager"
In general, the 長 suffix always means the head or leader of something.
チカン = "pervert", often specifies someone who attempts to touch or fondle women, rather than a mere vouyer or peeping tom.
が marks a subject
出没する = "to appear sometimes and remain hidden otherwise"/"to infest a place"/"to appear from nowhere then disappear again"
しました = formal past form

Definitions:　

なん = なに = "what?"
おい = "nephew"
の connects a noun phrase to the noun it describes
景太郎 = "Keitarou"
じゃない marks a negative rhetorical question
か marks a question (this makes it explicit that the じゃない is rhetorical)

Literal Translation:	Aaaaaaah...good bath.
Adapted Translation:	Aaaaaaah...this is such a good bath.
Alternatively, "this water feels so nice" is equally valid.

Literal Translation:	Are you knowing?
Adapted Translation:	Did you know?

Literal Translation:	If two people who love each other are at "Tokyo University"...
Adapted Translation:	If two people who love each other go to a place called "Tokyo University",

Literal Translation:	...they can become happy, it's said.
Adapted Translation:	it's said they'll live happily ever after.

Literal Translation:	When we become large, let's go to Tokyo U, the two of us together.
Adapted Translation:	When we grow up, let's go to Tokyo U together, okay?

Literal Translation:	When we become adults, let's definitely meet at Tokyo U.
Adapted Translation:	When we grow up, we're definitely going to Tokyo U, okay!?

Literal Translation:	I understood!! Tokyo U!!
Adapted Translation:	Okay, I'll be there!!

Literal Translation:	With that sort of reason, for now I am being a two-time rounin.
Adapted Translation:	And that's why I'm now a two-year rounin.

Literal Translation:	I, who was finally chased out of my home, came to that hot spring area.
Adapted Translation:	After finally being chased out of my home, I went to a certain hot spring town.

Literal Translation:	It was definitely supposed to be in this area, but...
Adapted Translation:	I was sure it was around here somewhere...

Literal Translation:	This place is the hotel which grandma is managing.
Adapted Translation:	This is the hotel grandma runs.

Literal Translation:	Grandma's grandchild, Keitarou.
Adapted Translation:	It's your grandson, Keitarou.

Literal Translation:	Huh? Are grandma and the people of the hotel absent?
Adapted Translation:	Huh? Where is everyone?

Literal Translation:	Grandma's room.
Adapted Translation:	It's grandma's room.

Literal Translation:	Will I have her let me wait in here?
Adapted Translation:	I guess I'll just wait here.

Literal Translation:	I'll be a bother.
Adapted Translation:	Excuse me...

Literal Translation:	Oh! Isn't this quite large?
Adapted Translation:	Oh! This is pretty big.

Literal Translation:	Definitely, I am 48th percentile, and my English is hopeless.
Adapted Translation:	It's true that I'm in the 48th percentile, and my English is terrible...

Literal Translation:	Math and Japanese and history and biology are all completely hopeless, but...
Adapted Translation:	I'm completely hopeless at math and Japanese and history and biology too, but...

Literal Translation:	Aren't they all hopeless!?
Adapted Translation:	Wait, that means I suck at everything!

Literal Translation:	I'm really a man with no elements which would make me popular with the opposite sex.
Adapted Translation:	There's really no reason at all for girls to like me.

Literal Translation:	One time is good so I want to date with a girl.
Adapted Translation:	I'd really like to go on a date with a girl, even just once is enough.

Literal Translation:	No, in this situation, even just to be able to talk is fine.
Adapted Translation:	No, at this point I'd settle for just being able to talk to a girl.

Literal Translation:	After all, these twenty years of my life...
Adapted Translation:	After all, for the past twenty years...

Literal Translation:	Folk dance partner always man.
Adapted Translation:	I was always partnered with men for folk dancing.

Literal Translation:	At this rate my whole life I also won't get a girlfriend.
Adapted Translation:	At this rate I'm never gonna get/never be able to get a girlfriend.

Literal Translation:	Around now, how is she of that memory doing?
Adapted Translation:	I wonder what that girl is up to now...

Literal Translation:	Now, I faintly remember her name and face.
Adapted Translation:	I can barely remember her name or face anymore.

Literal Translation:	If I think (about it), in the span of twenty years...
Adapted Translation:	Come to think of it, over the last twenty years...

Literal Translation:	I was popular (with girls) only that one time.
Adapted Translation:	...that was the only time a girl ever liked me.

Literal Translation:	Isn't this an open-air bath?
Adapted Translation:	It's an open-air bath!