MSAC is a rare and unusual disease that manifests when strong emotions like affection, vindictiveness, or regret towards a specific individual intensify. Its symptoms vary, and there is no established cure. Mitsuri, a gay man with a male love interest, finds himself the object of affection from Io, a new part-timer at his workplace. Io, despite his excellent memory, struggles to understand his own feelings and possesses a certain aloofness. Though Mitsuri initially suspects Io is mocking him, he gradually becomes aware of Io's presence.
