Onnanoko

Onnanoko is a hidden opponent in the game Wrecking Crew '98, faced in "Stage B", which is unlocked by defeating Gotcha Wrench within three minutes. Defeating her unlocks her as a playable character in the multi player mode, as is the case with all opponents in the game.

Trivia
Her name literally means "young girl" (derived from Japanese 女の子 = onna no ko), an obvious reference to what she is.