Yamikadou Meijirou is an ordinary highschool boy. After saving a loli devil, he discovers that he was born with the Seal of Solomon on his tongue, a special power that allows him to control all forms of sorcery and devils. He also discovers that he will die in three years as every use of his power uses up his lifespan.
He is told that the only way to save himself is to establish a contract with the twelve Starlight Maidens who were born with a special sign somewhere on their body, and to do so he must lick their sign with his tongue where his sign is located.
The MC then begins living alone with a loli devil in his room while seeking out the twelve Starlight Maidens to lick the signs on their bodies.