Outlaw Cop (1976)

Original title: やさぐれ刑事

A bad cop is engaged in a violent chase to catch a yakuza boss. In his absence his wife runs away with another man, who turns out to be the very same man that her husband is hunting. Once he discovers this, he loses his nerve and turns in his badge. But the chase turns into a personal vendetta where the ex-cop plans to wipe out the entire gang.