新遊侠伝 (1966)

In this town, Kagosuke and Ryukichi of the Okamoto family, who are deeply committed to the yakuza way, are straightforward and justice-loving hot-blooded men. However, their slight clumsiness is a flaw, but they are extremely strong in fights, and there's no one who can match them. They are head over heels for Osen-san. They are both desperately unwilling to yield even if the other is a brother.

Unfortunately the movie 新遊侠伝 is not yet available on HBO Max.