Joonha is a normal, healthy boy of sixteen who has cruised through life without too many problems. Imagine his surprise when a recent trip to the bathroom suddenly reveals that he's not normal at all! With a shriek of "Oh, my God!", he finds himself missing, well, something he never thought he could live without. As it turns out, his family is abnormal in the weirdest possible way. After puberty, their chromosomes undergo some kind of mutation, which converts their bodies into the opposite sex!