Erm I don't think you realize how dangerous the yakuza (at least in real life) is. I'm pretty sure yakuza have connections in the police and I don't think they treat traitors very well. Given his circumstances this is a pretty realistic conflict.
Even gangs in America are hard to get out of.
Had a friend in middle school and high school that was beaten within an inch of his life for wanting to leave the one he was in. He was about to become a big brother and didn't want his baby sister getting tangled up in it so he asked to leave and the only way they would was if he was hospitalized.
The Yakuza thing is annoying. Like...can't he work together with the police? Or run away with the MC? Fuck his family if they don't even ask for his opinions.