As a schoolgirl in Kobe, Otsuji was an Asian Junior karate champion, then later enrolled at Seoul University to study Korean and tae kwon do. She lost by TKO to Yoriko Okamoto in 1999. She had hoped to go to the Sydney Olympics in 2000 but was unsuccessful in making the national team. She returned to Japan and enrolled at Doshisha University in Kyoto, where she became interested in politics.