Daily Bunshou: A Geek Freaks Out

甲：伊藤君って知ってる？
乙：うん。あのコンピュータおたくの人のこと？
甲：そう。彼って短気で、すぐキレる。
乙：へえ、意外。一見、おとなしそうにみえるのに．．．

君 - くん - suffix for relatively young men (usually)

• This kanji, when used not after a name, can mean "you." It's then pronounced きみ and is either a very casual or a demeaning way to refer to someone. You can hear it used all the time in anime, such as in one of my favorites, Hikaru no Go. Hikaru and others in the Go organization refer to their subordinates or rivals as "きみ". Hikaru himself, rude boy that he is, frequently uses オマエ, and very inappropriately, too.

って - quotation mark

• In this case, って means "about." It's shorthand for について, which means "about."

コンピュータおたく - computer otaku, computer freak, nerd, etc.

短気 - quick temper

キレる - to cut well, to be cut, to snap

• This word in kanji is 切れる. Why, then, did our 文章 writer choose to use katakana? "It's more casual."
• What's being cut? Why, the string that Itou holds his patience with! See this bunshou for more on the 忍耐の緒 idiom.
  

意外 - unexpected

一見 - at first glance

おとなしそう - looks nice, looks docile, looks quiet

• 大人しい is "obedient, docile, quiet." Adding そう (and dropping the extra い from this い-adjective) creates a sense of appearance. You'll hear this constantly in 「おいしそう！」, referring to the appearance of deliciousness, as opposed to おいしい, which is said after you've already tasted it and confirmed the appearance.
• 大人 means "adult." 大人しい perhaps comes from the word for "adult." But perhaps not. True Japanese people do not speculate about the origins of their words, even if the sounds and the kanji are the same! I would love to do some heavy research on this, but I'm still somewhat too weak to read the material online. There is some discussion about it here.
  
• A similar-sounding word: 音無し, "silence, wait and see". This combines the kanji for sound 音 with the word for without 無し, literally meaning "without a sound." However similar, 音無 is completely unrelated to 大人しい.
  

みえる - to seem. Also the spelling of the potential form of 見る.

のに - although, but yet, in spite of (this is beginning to intermediate grammar, and I'm not quite sure how to use it yet)

Translation:

A: Do you know about Itou?

B: That computer geek? Sure.

A: About that guy... he's got a really short temper. He can just snap, like that!

B: Really? That's weird. And he looks so quiet and good-natured on the surface...

Notes:

1. 甲 and 乙 are traditional ways the Japanese can indicate Speaker A and Speaker B. I've seen it done in my Japanese class as ア and イ, but maybe that's because a lot of the students are uncomfortable with kanji.
2. You might have noticed that my translations are not word-for-word. That's because I hope to have as many Japanese natives as English-speakers reading these Daily Bunshous. A word-for-word translation is not useful to people learning English. For example, let's look at a word-for-word translation of the last line of dialogue: "Oh, (that's) unexpected. Although, upon first glance, (he) seems quiet..." That's terrible English. I hope that Japanese speakers can get a lot out of my translations, even if they are hard to understand. Plus, I try to carry the connotation of the original into the English, so Japanese learners can understand the general feeling.