Welcome to Happyland, an extreme amusement park! The Komiyas are a happy family, with no apparent problems. The parents love each other and are kind to their two children. The kids are brilliant students and in good health. In short, the ideal family that has everything they need to be happy! At least that's what they believed. Until dad decided to take the little tribe to spend a day at Happyland Amusement Park. In this park with deadly attractions, the most shameful secrets will emerge. Because in Happyland the curtain caller is Mr. Rabbit, and by the time he's all done, everything will end in tragedy.