Curious about why her best friend's boyfriend left her for another man, the determined Eiya Arakawa proposes a meeting with the ex-couple to find out. At a café, Yuuga Oota agrees to answer Eiya's questions only if she can accurately deduce the relationship of another couple nearby, which she succeeds in doing on her first try. Impressed by her quick wit and intuition, Yuuga introduces her to the idea of the Slave Control Method (SCM)- a powerful device that can turn people into slaves. When two people equipped with SCM devices engage in a duel, the technology takes over their minds. After the duel, the loser becomes obligated to obey and serve the winner. Desiring to test his skills, Yuuga convinces Eiya to act as his backup in case he becomes a slave. In exchange, he offers her access to 10 million yen to convince his potential master to release him from servitude. Though uncertain at first, Eiya is moved by Yuuga's words and agrees. But when a shadowy organization begins amassing slaves at an alarming rate, Eiya finds herself caught in a far more dangerous game than she ever anticipated.