@Sparrow75 IMO in many ways Kurata is more like a classic loner/introvert--just a quietish, shy-ish guy. Which makes it rather a problem for him to be forced into the leader role, especially since he also sees himself as significantly less talented than at least two of the other members. He is perhaps less complex in the sense that he doesn't seem to have a lot of major dysfunction going on. And he's a less extreme personality generally than some of the others--he's not a
complete loner, he's not
extremely shy, just more of both than average. I actually like him precisely because he's a nuanced person who has to be drawn all the more carefully because you can't hang his characterization on one or two extremes.
Momoya is an unusual guy and while the tag "loner" fits, I'm not so sure about "introvert". Superficially pleasant and sociable, has a good surface going on, but doesn't seem to relate to anyone at a level deeper than surface--doesn't typically
care about people, and people don't typically care about him. He may have given up ages ago after first finding that people pull away from him because he's too good at everything, too effortlessly, but if so it was so long ago that he's left with only a vague feeling that maybe this is unsatisfying and not quite how things are supposed to work. Certainly an interesting character, but quite atypical for introvert types. Most introverts I've known, including myself (more when I was younger), tend to have no problem relating pretty closely to people, just not very
many people. Only willing to socialize with a few at a time, only wanting to be close to a few total, and generally more quiet the more our number threshold is exceeded. Momoya is quite weird as introverts go--he'd actually probably be fine at a
party, a place where nobody knows each other that well and he can easily skate along the surface, where most introverts loathe them precisely because they have to deal with big numbers of people they don't know well. But in the past when he's gotten involved on a more extended basis with smaller numbers of people, like in a band, he's eventually given up, unable to get close . . . where more typical introverts in that sort of situation would bond with at least a couple in that small group and in time become relatively comfortable.
Momoya actually feels almost like a psychopath . . . a psychopath who doesn't happen to be evil, and who actually doesn't
like being one and would like to be able to feel for people the way other people seem able to. But a psychopath, in the sense of not really grokking emotional experiences like love, friendship or empathy and covering up with a smooth facade. I don't think he quite is one, and there's a definite feeling that his emotions are more dormant than completely absent. Definitely an interesting character.