アンダーニンジャ

Kuro Kumogakure is a jobless high-school dropout coasting through life on borrowed food and free drinks from his neighbors, and also a low-ranking member of Japan's hidden ninja network. The Allied occupation ordered the country's ninja organizations dissolved after the war; instead they went underground, burrowing into companies and institutions worldwide until some 200,000 of them were working in the dark. Kuro's idle life ends when the network finally hands him a job: go undercover at a Tokyo high school and find out what is going on inside it.