Isaka was born in Saitama Prefecture on January 25, 1976. She joined Nadeshiko League club Urawa Ladies in 1994. She was selected Best Young Player awards in 1994 season. In 1995, she moved to Prima Ham FC Kunoichi (later "Iga FC Kunoichi"). In 1999 season, she scored 21 goals and became top scorer and she was selected MVP awards. She was also selected Best Eleven 3 times (1999, 2000 and 2003).