When Sanpeita Kobayashi was a child, his lovely friend had to move away, but she vowed that in ten years, they would meet again—as husband and wife. Ten years later, Sanpeita is a high school student, but he hasn't forgotten the feelings they shared. Sanpeita awakes from a dream about his last day with her, only to have his morning interrupted. A weird robot girl is battling other robots in his bedroom, claiming to be his wife. The robot's pilot looks like none other than Sanpeita's long-lost, childhood friend. But who is she really? Why did she have to leave? And what does she have to do with the Mishima Electronics Corporation?

A young boy named Jiro finds his mother and sister murdered in his home. Falsely accused of the crime, he flees from his village and meets a priest named Tenkai, who has him kill a rogue ninja named Tarouza. After fulfilling that task, Jiro undergoes training to become a master assassin. Many years later, Jiro finds out that he was an orphan and his real father was Tarouza, who had worked for Tenkai until he aborted his mission when he fell in love with an Ainu woman. The young ninja discovers that the Shogunate was to retrieve the lost treasure of Captain Kidd and use it to once again isolate Japan from the rest of the world. Using the clues that Tarouza had kept secret, Jiro—along with the female ninja Oyuki and a slave named Sam—travels to Russia and America to search for the treasure in hopes of using it to extract revenge from Tenkai. (Source: ANN)

Transferring the human consciousness into a robotic "I-Machine" is now a reality thanks to the discovery of a valuable ore called "orichalt." However, there is the possibility of the consciousness failing to return to the host's body, rendering them stuck inside their new metallic frame for good. Such is the situation of members of the Excavate Company, a reckless band of I-Machine miners led by the notorious Grayman that aims to gather orichalt for profit. During a mining incursion, the group rescues Maya Mikuri, a student who was abandoned by her crew. Accused of stealing classified information on orichalt by her former colleagues, she joins the Excavate Company in hopes of clearing her name. They then begin an adventure that will change their lives—including that of Ido, an ace member of the group with no memory of his past. For the first time, Ido might have the chance to rediscover his true identity. [Written by MAL Rewrite]

Specials included on DVDs and Blu-rays. The series takes place in an alternate version of Japan called Great Japan (大日本国, Dai Nippon-koku), in an alternate timeline where the Tokugawa shogunate remained active and has remained semi isolated from the rest of the world after their defeat by American forces in World War II. And the Americans have bases on Okinawa and southern great Japan. The story takes place at Buou Academic School (武應学園塾, Buō Gakuen-juku), an academy located at the base of Mount Fuji where children of military families train to become samurai warriors. The academy is in the middle of a power struggle between Yukimura Sanada and Matabei Goto of the Toyotomi faction and the powerful student council that rules the school, and Muneakira Yagyu, the owner of the Yagyu Dojo, and the mysterious Jubei Yagyu are dragged in the middle of the conflict.