Mana, a cheerful teenage girl who travels from town to town arrives in the central city of Toykyo to enjoy herself. There, she meets a not particularly bright boy named Showtaro, who she soon discovers is a "Clown": a human who can use a special power in exchange for a specific condition. The boy can use the power of various animals by biting one of their bones, but his condition is to achieve "one good deed every day". Mana soon decides to help Showtaro in his journey to find his long-lost friend Emine.