Yukinari Sasaki looks young but is actually a sophomore in high school. Besides his baby face he thought he would be treated like any other boy, but because of his small size he has been bullied by girls ever since he was little. He has developed such a fear of girls that he not only goes into hives but has a full blown allergic reaction to them. After getting in a dispute after walking into his bathroom on his neighbor he is kicked into his bathtub and is transported into a world which has very few man and consist mostly of women. There he meets a girl named Miharu who for some unknown reason doesn't cause him to break out in hives or get rashes.