Writing dialogue in fiction is...an art?...a talent?...a skill? All of the above? It is tricky because it should sound like speech, but it cannot be an exact reproduction of speech. Real speech is full of verbal tics, dropped thoughts, repetition, and extra words. If you've ever read an exact transcript of ordinary people speaking you know how boring it can be.
Adding to the challenge is that ideally every character should have his/her own way of expressing himself/herself. His own vocabulary, turn of phrase, level of usage, and more. In a way, Japanese writers have it easy because there are words that only men use and words that only women use. Also by verb endings and other grammatical markers, it is clear whether a superior is talking to a social inferior, a man to a woman, an adult to a child, and more. It means that Japanese fiction does not (usually) need a lot of "he said/she said" to make it clear who is speaking and the relationship between the characters.
Another challenge I had in Getting Oriented—beside trying to give each character his/her own voice—was to distinguish the times when the main character was speaking in English and when he was speaking in Japanese or being spoken to in Japanese. I didn't want to clutter the pages with words few readers would understand, so I've put all of the "Japanese" dialogue into italics. And to make that dialog sound different, I tried (not always successfully) to first construct the sentences in Japanese and then translate them into English. I think—I hope—this gives the Japanese dialogue a different feeling than the English exchanges.