Brother (2001)

When Yakuza gangster Yamamoto is forcibly retired from his clan after a hostile takeover, he flies from Tokyo to Los Angeles to find his younger half brother Ken, whom he believes he has been financing through college. When he finds that Ken has dropped out of school to run a sloppy drug-dealing operation with his buddy Danny, Yamamoto slaps him on the back of the head in disgust, then shows the motley crew how to take over the LA underworld, Yakuza style. In the most violent ways imaginable, Yamamoto transforms the ragtag gang into a styling posse of professional punishers and schools them in a kamikaze code of honor that puts all other forms of gang bonding to shame.