Tokyo, in the Showa 40s. Joe Yabuki was living an aimless life until Danpei Tange discovered his boxing talent. However, due to certain troubles, he was sent to prison. There, fate led him to meet the professional boxer Rikiishi Toru. While learning boxing from letters sent by Danpei, Joe competed with Rikiishi in prison, each proving their strengths. After their release, both men grew within their respective professional weight classes. Later, Rikiishi wished to face Joe one more time before his world championship match. Their passion moved the gym owner, Shiraki Yoko, and she made this showdown a reality.