Keiichi Sawai is the biological Father of Soichiro Tachibana and Otomi Tachibana. He is Mayumi Sawai's first husband, he passed away before Soichiro Tachibana was six years old. He used to be the ace pitcher for Meisei High School. At some point he stopped playing baseball altogther but he supported his children going into the sport. Even buying Soichiro's first baseball.