The Underworld.

Yakuza boss Furuya leans more and more on his protege Takao Shoji, though Shoji has become romantically involved with Furuya's mistress, Natsue. Furuya himself has fallen in love, with a nurse after his recent hospital stay. As the gang grows more jealous of the favoritism Furuya shows Shoji, they decide to reveal Shoji's relationship with Natsue. But Furuya's affection for Shoji cannot be easily destroyed, even in the gang war that erupts.