Hes probably wanna in, yakuza was somewhat a police force in the beginning right? Just going back doing local shit and help out the police against foreign gangs is probably enough.
they can’t really afford to. toushou and the police already have a dangerous relationship, and like toake said, the police still have the upper hand - not to mention the extreme losses toushou has suffered.
plus, after this, I’m sure anai will be extra careful to protect himself and his family.