The ill-fated Tatsumi, who used to live alone, is now the unwitting host to a growing menagerie of undersea creatures. His bathtub has become the abode of the self-indulgent merman, Wakasa, with regular visits from his aquatic friends—the octopus Takasu, the shellfish Maki, the jellyfish Mikuni, the shark Agari, and the newest member, the starfish Goromaru. With the New Year upon them, it's time for sweets, bean-tossing and more, but can a tub this small possibly hold a crowd this large?