Gaea Japan
Miyaguchi started her professional wrestling career in 1994, working under her real name in JWP Joshi Puroresu. She made her debut on December 4, 1994, in a match against Rieko Amano. Originally working as a "junior" wrestler in not only JWP, but also All Japan Women's Pro-Wrestling (AJW) and Gaea Japan, Miyaguchi went on to win the Junior Championships in both JWP and AJW. After the end of her junior days, Miyaguchi adopted the new ring name Ran Yu-Yu, which she held for the rest of her career. Under her new ring name, Yu-Yu went on to win the JWP Openweight Championship in 1999. She remained affiliated with JWP until October 2002, when she officially joined Gaea Japan full-time.