Once believed to have vanished after the war, Japan’s ninja clans secretly survived—now said to number over 200,000. While elite operatives work behind the scenes in national-level conflicts, ordinary ninjas struggle to find jobs in modern society. Among them is Kurō Vân Âm, living like a full-time NEET—until a sudden crisis at Ninomaru drags him into a whirlwind of danger, destiny, and unexpected ninja chaos.