Break your chastity!(純潔を破る！)

A brother who suffers from incest tries to commit suicide with his sister, but the sister dies and only he survives. A man lives with that feeling of guilt... One day, when I helped a girl who was attacked by her thugs, she looked like her dead sister. Moreover, she lost her memory from the shock of being raped. And the strange cohabitation life of a man and a woman begins...