"Chan" seems to have more than one meaning,
depending on context. Technically, "miss" is the
best translation, although it can be used in other contexts
to either show fondness or mocking. To call an adult male
"chan" - unless one is VERY familiar with him -
is an insult; however, if one is as familiar with that man
as Hokuto is with Seishirou, the "chan" takes on
a sense of lightly teasing closeness. (Note: to call a young
man -chan, unless he is very young or you are very
familiar with him, is also insulting, since it implies that
he is not "manly;" it can indicate either extreme
closeness and fondness or extreme insult and dislike. Gotta
love this language.)
"Kun" is also sometimes translated "Mr.,"
although this doesn't really explain it. It's a much younger
term; it is perfectly acceptable to call a boy (and on SOME
occasions a girl) younger than you are "kun" as
long as they are younger than you are. It's an affectionate
term, although really not something one would use with an
equal; if Seishirou called Subaru "san" instead
of "kun," it would indicate equality - his use of
"kun" shows his understanding of Subaru's place...
underneath his own.
"San" is often translated as Mr. or Ms.
It's basically a polite form of address - but formal enough
that for a young man like Subaru to use it with Seishirou
indicates a certain pecking order. Subaru is acknowledging
Seishirou's age and standing over him.
"Sensei" technically can be translated as
"teacher" (i.e., schoolteacher), but for whatever
reason, it's usually applied to medical doctors as well (and,
I have just been informed, to writers). Basically, the kanji
here means that a sensei is one born before you - i.e.,
has knowledge and experience that you don't, and therefore
can pass those things along to you. Cool, huh?
"Sama" can be translated "lord,"
"master," etc.; it's a term with a lot of power
- you wouldn't use this to address your teachers or friends.
"Sempai" - a polite term used for a student
older than the speaker. Showing respect.
"Shoujo" - literally "girl." Often
refers to either a girl or things that are "girlish,"
like certain kinds of Japanese comics.
"Kakumei" - revolution. As in,
"revolutionary girl Utena." See? It makes sense.
~_^
"Zaibatsu" - sort of a school
that's really a small town. The idea is to make everyone within
that educational community unified and self sufficient - everything
they need can usually be found there.