One day, when Hidaka Kishi is going to school with his close friend Kimiko, he notices a strange new song on his music player: "Who Killed Cock Robin?" Little does he know, a murderous game is beginning, with him as the target--the Cock Robin. Fourteen other players (called 'birds') are all competing to kill him, in exchange for making their wishes come true. However, one of the birds, Saedano Minami, seems to have other plans. To Hidaka's confusion, she decides to protect him, but what is her ultimate goal? How will Hidaka survive this deadly game?