Jun Kagami arrives as a transfer student at Doumori Elementary School, marked by intense shyness and social isolation that prevents him from forming connections. His profound loneliness drives him to depend on a supernatural entity he perceives as his sole friend: a mirror-dwelling clown named Pierre.

Kagami's insecurities and experiences of bullying render him susceptible to Pierre's influence. The clown entity exploits this trust and Kagami's emotional fragility, presenting itself as a supportive companion. Pierre provides Kagami with a mask imbued with supernatural abilities, which becomes a turning point. After acquiring the mask, Kagami begins acting strangely, coinciding with a series of unexplained accidents occurring at the school.

Under the mask's influence, Kagami transforms from a withdrawn child into an instrument of supernatural occurrences. His bond with the clown entity becomes central to the escalating disturbances, positioning Kagami as an unwitting catalyst for the conflict. This situation demands intervention to address the supernatural threat and Kagami's manipulated state.

Kagami's vulnerability to the clown stems directly from his background as a lonely transfer student unable to forge real friendships; this psychological state creates the opening for the entity. Resolution requires confronting the clown entity's true nature and severing its hold over Kagami. Following this intervention, his behavior normalizes, free from the entity's influence.