It's finals time, but tests aren't the only things stressing out Yuuta, who's literally being smothered with affection from his beautiful sisters: Chiyoko, who is feminine, caring, and coddles him; and Chinatsu, a strong-willed tomboy who desperately seeks his attention by picking on him. Who will triumph in this sibling love triangle?

Yuuta has always been close to his elder sisters, Chiyo and Chinatsu. The only man in the house, he falls in love with the caring and affectionate Chiyo; with her well-endowed body and love of cosplay, she gives her brother everything an adolescent boy could dream of. Envious of her siblings' intimate relationship, Chinatsu soon steps in, seeking Yuuta's attention. As a strong-willed and dominant tomboy, she is the exact opposite of Chiyo and starts picking on him and making aggressive sexual advances. With the situation at home changing dramatically, the siblings must find a way to sort out both their private and school lives and establish a compromise between conflicting interests.

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.

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.