Finally figured out what the hell that kanji was meant to be. Ryuuichi's using the construct 父親, chichioya, which literally says "father parent". I've never run into it before. He's also using it without the formal o- or any honorific suffixes, when talking to Mitsurugi about Mitsurugi père. No dictionary will tell me definitively what that one means, but he is definitely doing it on purpose -- when explaining to Mayoi in the office, he drops back and uses otousan, as she has been.

The oya part is also used in other constructs for people who are seen as parental figures, like oyakata (親方), a "coach" in martial arts, or oyabun (親分), "Boss" of a gang, or the don of a crime family, in a very tightly-knit sense. The implication is that this is someone you look to for guidance. The character is also used with a different pronunciation in a collection of adjectives and expressions that describe intimate relationships, with overtones of great affection. I'm unfamiliar with them, and given the amount of cheesy anime I've seen to date, this suggests that they are not used for romantic relationships. Overwrought people in dramas do scream stuff about being in love from time to time, but closeness in family or friend relationships is something not often overtly referenced -- you're more likely to simply describe someone as an "important person" or to speak of them in a familiar manner.

Mitsurugi also slips in his formality once and calls his father oyaji, a very casual term that falls somewhere between "Dad" and "my old man" on the scale. Between that and Ryuuichi's rather striking choice of terms, the overall impression is that Mitsurugi was very close to his father when he was a child -- a fact of which Ryuuichi is well aware, but also of which Mitsurugi would rather not remind anyone else, just in case they get to thinking of him as having feelings or something. He consistently says "Father" or "my father" in English, which is appropriate for his tone and sentiments, but loses some of the more ineffable shades of meaning.

Karuma, who took him in afterwards -- a particularly nasty thought, that, to anyone who knows how the case ends -- is always Karuma-kenji, Prosecutor Karuma, in much the same way that most people refer to Mitsurugi as Mitsurugi-kenji. (Except Ryuuichi, who's taken to thinking of him as Karuma no yatsu, "that Karuma guy," in his internal monologue. Not outright disrespectful fightin' words, since it's not to his face, but not friendly in the slightest.) It's an occupational title, not a family term, and sounds formal and rather icy in context.

There are also some tweaks to the story as a whole, effected by the change in language. In English, Edgeworth stops Phoenix after the second trial day and basically says, "I think it's time I told you everything." Because of the casual use of 'you' in English for 'general reference to people who are not me', it's easily interpreted as 'I should tell this to you, the lawyer who is running my defense, and probably your sidekick and whoever else you have tagging along this evening'. Things like these are often omitted in Japanese, and they have this ongoing love affair with tenses like passive-causative, so if this were what he meant, the Japanese would more than likely have a literal meaning more like 'thinking that this thing should now come to be told', missing basically all of what we English speakers think of as the important nouns.

It's not. It's directed from himself specifically -- he uses watashi, first-person singular, when it's not technically necessary -- at Ryuuichi specifically -- as in, he uses the familiar second-person singular kimi when he's been consistently using the familiar second-person plural kimitachi to refer to Ryuuichi and Mayoi and all -- with the meaning of 'I think that I should tell YOU this thing now' with an implied '...before you do anything else under the assumption that I'm still the good person you think you remember.'

This is why translations annoy me sometimes. No matter how good they are, you always lose something.