The Yakuza (1974) on Netflix

The presently private investigator and real-estate agent Harry Kilmer is bonded to Japan culture. In the end of World War II, he was assigned to stay in Tokyo, and meanwhile he felt in love with the Japanese woman Eiko Tanaka. In 1949, her Yakuza brother Ken Tanaka, who was missing in action in Philippines, returns to Japan. Harry proposes to marry Eiko, who is also in love with him, but she does not accept his proposal. With a broken heart, Harry decides to return to United States of America. He borrows some money from his close friend George Tanner, buys a small restaurant for Eiko and her baby daughter, and returns to his home country. After several years, his friend George asks Harry to return to Japan with his bodyguard Dusty to rescue his daughter, who was kidnapped by a Yakuza family, due to a weapon business. While in Tokyo and Kyoto, many revelations are disclosed to Harry about his close friends.