Rami-Chan No Ooeto Surogoku: Keio Yugekitai Gaiden Japan

The main character of the game (Rami Nana-hikari) is the grandchild of an ancient family with the mission of guarding the key that opens the Ark, Rami wears the traditional Kimono at the beginning of the first game, and later changes into the 'Super Ultra Cute Battle Suit' that is nothing more than a bunny girl costume, complete with bunny ears and tail.