I've never understood the "parent(s) had debt and ran away so suddenly the child is responsible for it" bullshit that's shown in stuff like this and Hayate no Gotoku. That's not how any of that works at all. It would actually be an interesting story if this could happen in real life.
It actually does happen in real life, with companies trying to foist debts on relatives. Thankfully my family knew to say 'no.' So I could see yakuza trying it.
Anyway... good story!