What would you do to save someone you love? All brothers Shoma and Kanba know is that, after collapsing in an aquarium and apparently dying, their terminally ill sister Himari was somehow revived by a Penguin hat that she had wished for. Now they're on an impossible mission, because the price of keeping Himari alive is to find a mysterious object called the Penguindrum, and they'll do anything to save their sister. Anything. As they travel separate paths in their search, they'll have to unravel complex riddles, make alliances with strangers they know they shouldn't trust, and question the very fabrics of time and destiny..