Yamikadou Meijirou is a fifteen-year-old high school student who tries to ignore ghosts and the occult, despite possessing a hidden power that wards off supernatural phenomena. One night he saves a devil named Lato Mii, and learns that he carries the Seal of Solomon, known as the Ring of the Star Contract, on his tongue. This mark grants him the ability to command all sorcery and devils, but each use of the power drains his lifespan, leaving him with only about three years to live. The only way to escape this fate is to locate and form a contract with twelve girls called the Starlight Maidens, each of whom bears a unique star-shaped sign somewhere on her body. Because Meijirou's own sign is on his tongue, the contract ritual requires him to lick the maiden's mark. The story follows his search for these twelve maidens, a quest that draws him into battles against demons, confrontations with rival factions such as the Excommunicated Crusaders, and rekindled connections with childhood friends and fellow students. The setting is a modern school environment where everyday life collides with supernatural combat and romantic entanglements. The narrative blends action sequences, comedic situations, and evolving relationships as Meijirou contends with his dwindling time, the growing circle of maidens, and the escalating threats that come with wielding the Star Contract's power.