Animal Hamaguchi
In 2003, Mizushima entered All Japan Women's Pro-Wrestling (AJW) dojo, where she was trained by Animal Hamaguchi in not only professional wrestling, but also mixed martial arts. On December 19, 2003, Mizushima made her MMA debut at an AJW event, losing to Mika "Hari Hari" Harigai at 2:10 in the first round, after being knocked out with knee strikes. She has not participated in any mixed martial arts fights since. Mizushima's professional wrestling debut took place on January 3, 2004, when she faced Hiromi Takahashi at an AJW event in Korakuen Hall, Tokyo. Mizushima would leave AJW, which was battling severe financial difficulties, later that year.