The Rough One(1969)

A tale of wannabe yakuza youths. When not cooking up scams with his buddies, Zenkichi develops a crush on Taro's disgusted sister, Miki. But soon the young hoods run afoul of their underworld idols when they rob the wrong gang, led by brutal boss Konno. When Zenkichi's pals start to bite the dust, he hooks up with a more traditional yakuza, Tetsugoro, to retaliate.