Mai was abused by her parents in her childhood. Now she is 20 years old, spends meaningless days hanging out with her best friend Kana. One day, Mai encounters a possible "cosplay killer" in the news, he is said that he murders people repeatedly wearing mask and costumes of cute anime characters. Mai prepares to be killed, but the killer just stares at her and then disappears. Mai feels anxiety, but at the same time, she begins to associate the cosplay killer with "Shinji", the man who saved her in the past. Meanwhile, the cosplay killer strangely attracted to Mai. He hides that he is a killer and approaches her. While Mai hides her trauma and the killer hides his true self, they gradually grow closer and are strongly attracted to each other by an invisible "something". However, to know what they are hiding each other only means their separation.