I think it's how you refer to yourself, but it's been a while since I learned. Like there's three or four versions of "I", watashi, watakushi (very polite), and I forget the other two but one is extremely informal and possibly makes you sound like a delinquent.
Edit: ore and boku, can't remember which is the informal one, somebody who knows more step in and add some extra context please.
Probably that then! I study Chinese (Mandarin) now, so that's a very unusual character to me. Apparently it has a similar meaning but it's only used in regional dialects.
Availability of native speakers local to me, and the fact I was initially attracted to Japanese by the characters and ended up essentially studying Chinese when researching their history. I may return to Japanese later, there's certainly plenty of study materials.