In the Edo period of Japan, a samurai’s life belonged to his lord. On the battlefield or in the home, a loyal samurai must always obey his lord’s commands. This is the tragic story of one such loyal samurai, whose love for his family forced him to make the ultimate choice of disobeying the wishes of his lord.

Set during the Meiji Restoration period of Edo era Japan, Naoyuki belongs to the 8th generation of the Inoyama family, a wealthy family known for finance & accounting. He is also a gifted mathematician and uses the abacus with extreme skills. Naoyuki works under the declining Kaga domain. Because of this, Naoyuki and his wife Koma suffer hardships as their stature and wealth dissipates.

Ueda joins other professors to debunk a spirtualist, Midorikawa Shouko, who claims she knows when people will die. The professors die one by one. Introduction of Yabe's Otaku assistant, Akiba.

In the aftermath of the most devastating conflict mankind had ever experienced, the tiny island of Shikotan became part of the Sakhalin Oblast... and on the unhealed border in this remote corner of the world, friendship among children from two different countries timidly blossomed, striving to overcome language barriers and the waves of history. Inspired by true events.