After heading off to a duel, Mr. Doi has gone missing──!? After accepting a challenge to a duel from the Tasogaredoki ninja, Monamon Moroizumi, Mr. Doi completely vanished without a trace. Upon hearing the full story from Monamon and his superior, Konnamon Zawatari, Mr. Yamada and the sixth-year students of the Ninjutsu Academy set out to search for Mr. Doi. Meanwhile, in Class 1-Ha, who know nothing about the situation, Konnamon and Monamon take over the teaching duties in place of Mr. Doi and Mr. Yamada!! Though exhausted by the unusually tense classes, the carefree first-year ninja pupils of Class 1-Ha go about their days as usual— But a creeping white darkness begins to encroach upon their peaceful daily lives. What is its true form…? Can Rantaro, Kirimaru, Shinbei, and the others restore the everyday life of the Ninjutsu Academy!?