Thanks to its prosperous people and breathtaking scenery, Great Japan is often envied by all nations. However, the land is threatened by a grave danger that only the enigmatic Master Samurai can protect against. When Muneakira Yagyuu, a young samurai, is summoned by the student council to Buou Academic School, he finds himself at the center of a gripping conflict. As the Tokugawa Shogunate-run school prepares the children of nobility to govern the country, Muneakira is thrust into a violent attack upon arrival. Amidst the chaos, a mysterious young woman named Juubei Yagyuu appears out of nowhere, kissing Muneakira and unlocking a hidden power that saves them both. Muneakira must uncover the truth about the Master Samurai and Juubei's origins to protect his homeland from a terrifying threat that could shatter Great Japan to its core.