Kamba and Shouma Takakura have taken care of their sickly younger sister Himari since their parents disappeared years ago - that is, until the day she died. But as the boys grieve by her hospital bed, Himari sits up, adorned with a strange penguin hat. Suddenly, the three of them are transported to a vibrant world where the hat, using Himari's body as a puppet, charges these brothers with a task: find the Penguin Drum and their sister's life will be saved! Now aided by some odd penguins they received in the mail, the duo must find this mysterious item or risk losing the sister they care for so much. However, they aren't the only ones with their sights on the Penguin Drum, for new enemies await them around every turn, all connected in ways they would have never imagined...