Onotora Shu is beautiful and perfectly complex. After the death of his parents, he was raised by a family friend Joichiro. But one day Joichiro dies. It was only after his death that Shu learned that his guardian had been a legendary assassin in the past. And although the police recognized Joichiro's death as an accident, Detective Shiori suspects that it was a murder committed by a young mangaka Mitsuki.
To avenge Joichiro, Shu decides to kill the girl himself. But instead of murder, he falls in love with her.