In "Love Tyrant," Seiji Aino's everyday routine is disrupted when Guri, a strange girl in cosplay attire, appears at his door and threatens his death unless he kisses her within 24 hours. Taking it as a romantic gesture, Seiji complies, but he does not realize Guri is actually Cupid wielding a Kiss Note—a device that forces any two names written in it into a romantic relationship. Guri confesses she accidentally wrote Seiji's name while daydreaming about yaoi scenarios, making their kiss ineffective. Still, she warns that if Seiji does not form a partnership soon, she will die, and he will be condemned to a lifetime of celibacy.
To escape this outcome, Seiji targets the popular Akane Hiyama, but her response is unexpected—she becomes dangerously fixated after learning of his kiss with Guri and attacks them both. In the chaos, Guri uses the Kiss Note to forcibly pair Seiji with Akane, stopping the fight. Driven by her growing feelings, Guri also links herself to the duo. This strange arrangement turns Seiji and Akane into temporary angels, forcing them to help Guri with matchmaking or face eternal damnation in hell. Now stripped of his normal life, Seiji must cooperate with these unconventional girls on their matchmaking mission.