The story centres around the lives of three siblings, Takakura Kanba, Takakura Shouma and their terminally ill sister Takakura Himari. Himari passes away after going out on a trip with her brothers. She was however, miraculously saved by a spirit thriving in a penguin-shaped hat. In return for her extended life, the twins must search for an item known as the Penguin Drum with the aid of three penguins which are visible only to the siblings.