Sonatine

Kitano plays Murakawa, an enforcer for the Tokyo-based yakuza tired of gangster life. He is sent by his boss to Okinawa, supposedly to mediate a dispute between their allies, the Nakamatsu and Anan clans. Murakawa openly suspects the assignment is an attempt to have him removed and even beats up one of his colleagues, Takahashi, whom he distrusts, but ends up going with his men. He finds that the dispute is insignificant, and while wondering why he was sent to Okinawa at all, the group's temporary headquarters are bombed and they are then ambushed in a bar, leaving several of his men dead.Fleeing to the seaside, the survivors take refuge in a remote beach house belonging to a brother of one of the Nakamatsu members and decide to wait for the trouble to blow over. Whilst spending time at the beach, the group engages in childish games and pranks and begins to enjoy themselves. However, the games frequently have a violent undertone. When two of his men alternate shooting at a beer can on each other's head, Murakawa turns it into a game of Russian roulette. Putting the seemingly loaded gun to his head, he pulls the trigger on the last chamber. The chamber is revealed to be empty and Murakawa is unharmed.He later dreams of the Russian roulette game, although in his dream, the revolver is loaded and he is killed. When he wakes up, he walks down to the shore. He sees a car pull up, and a man drags a woman into the sand and attempts to rape her. Murakawa stoically watches for a while and then walks past them. When the man realizes Murakawa has been there the whole time and shouts at him, Murakawa headbutts him. The man pulls out a knife and threatens Murakawa. The woman saves Murakawa by shooting the man dead. She then joins Murakawa and the gang at the beach house, and comes frequently to visit, spending time with Murakawa.Later, an assassin disguised as a fisherman appears. He kills several people, including the boss of the Nakamatsu clan and one of Murakawa's men, in the middle of a Frisbee match. Learning that Takahashi is arriving in Okinawa, Murakawa and two of his surviving men visit his hotel. Unable to find him at first, they unexpectedly run into Takahashi and the assassin in the elevator, which results in a shootout, killing the assassin and Murakawa's men. Murakawa learns from interrogating Takahashi that their boss had intended all along to partner with the Anan clan and had sent Murakawa to Okinawa in order to get killed and thus take over his turf. He also learns that the boss will be meeting with the Anan that night in a hotel. Takahashi is killed and Murakawa sets off with the only survivor of the group, a member of the Nakamatsu clan, who helps him by rigging the electricity in the hotel to go off at a certain time. Murakawa tells the woman that he may come back, and the woman promises to wait for him.Later that night, while waiting for all the yakuza to arrive, the Nakamatsu member asks Murakawa to take him with him, but admits that he has had enough when Murakawa asks. When the electricity goes off, Murakawa goes into the hotel and slaughters both clans with an assault rifle. The next morning, while the woman continues to wait for him, Murakawa drives to a spot near the beach and commits suicide by shooting himself in the head. The scene then switches to the car and the horizon and slowly fades.

Question: Why does Murakawa go to Okinawa?
Answer: To mediate a dispute between two clans