Japanese Godfather(1989)

Original title: 일본대부

Released from prison following the bombing of Hiroshima, Kang Dae-sun tries to return to Korea but, because of the chaos at the end of the war, fails to secure passage. He and his former cellmate Ok Man-sul become gangsters but spend a good deal of their time fighting communist sympathizers. When the Korean War breaks out, Dae-sun gives up the idea of ever returning home and concentrates on rising in rank to become the most powerful gangster in Japan.