Quote Originally Posted by Magik 13
-Sensai used as a title for teachers/professors
It's spelled sensei. (Actually, it's spelled せんせい, but "sensei" is the correct Romanized transcription.)

Although your notes on honorifics are essentially correct, I'd like to make a comment about Japanese honorifics and the use thereof in fan fiction, largely gleaned from manga and anime. Actually, it's a comment about using "foreign" words in English-translated dialog in general, but it's particularly endemic to Japanese-to-English dialog.

Writers love "fanboy Japanese" because it sounds so cool and... Japanese. The problem is, unless you are really knowledgeable about Japanese culture (and reading manga does not count), you're going to get it wrong. Especially if you try to pepper your dialog with "-kun" and "-san" and "-sama" and "-chan," etc.

Yes, Japanese people, when speaking Japanese, use these suffixes in addressing one another. If you are writing dialog in English, however, even if the characters are actually supposed to be speaking Japanese, I would strongly suggest you drop the honorifics and write "normal" English dialog.

If you write:

"Good morning, Professor Snape," Jin greeted him in Japanese.
then we can assume that Jin actually used the correct Japanese title. Maybe what he actually said was "Snape-sensei," or maybe he said "Snape-sama," or maybe he used any one of a dozen other titles of respect used for teachers/mentors, many of which most gaijin have never heard of. The point is, it would have the same significance in Japanese as calling him "Professor Snape" in English. You aren't actually writing the dialog in Japanese, and you're not trying to translate all the slang and idioms you're writing in English, even though the characters would actually be using the Japanese equivalent of those idioms, so there's no need to include the Japanese titles in the dialog either.

Japanese rules of etiquette are very complex and difficult for foreigners to grasp -- there are subtleties in modes of address that you're not going to get even if you've taken a few semesters of Japanese and are sort of able to understand it. Nothing screams "clueless fanboy" more than having your characters address each other (inappropriately) as "-chan" or some other diminutive or honorific you got from a manga or Google.

The only place where it's really appropriate to include these words is if the characters are actually speaking English, but deliberately add a Japanese word, like if a Japanese student said (in English): "Good morning, Snape-sensei." (And that would still sound like clueless fanboy dialog, because if the student has learned enough English to say "Good morning," he's probably learned how to use "Mr." or "Professor" or "Sir.") Yeah, sometimes characters might stick a "chan" or "sensei" into their conversation for effect, but generally, not. I've known quite a few Japanese people, and almost never do they use Japanese honorifics when speaking in English (especially to non-Japanese), unless they are being deliberately ironic or making a joke.

Likewise, if your dialog is in Japanese, you might include the honorific by way of emphasizing its significance, e.g.,

"Good morning, Snape-sama," the Japanese Second Assistant Undersecretary of Foreign Magical Affairs greeted him, with a deep, respectful bow. Apparently his superiors had informed him of just who this ugly, greasy-haired gaijin represented...
But otherwise, I would recommend just leaving the fanboy Japanese out of your story.

(Note, incidentally, that I do not claim to be completely immune to this syndrome myself. I've occasionally used "foreign" words for effect in my stories, and while I try to research their usage pretty thoroughly, I might not have always gotten it right.)