In a world where people and inner demons called Shinkis normally coexist, high school student Kei despises these entities and has spent his entire life suppressing the Shinki that resides inside him. Living with his aunt, Kei keeps his true nature hidden, but a sudden major incident forces his Shinki to break free. This unexpected release draws him into a chaotic supernatural conflict and entangles him with others who have their own relationships with their inner demons. As Kei struggles to control his unleashed Shinki, he must navigate a blend of school life, comedic misunderstandings, and budding romance while confronting the truth about the demons within.