NIPPON SANGOKU: The Three Nations of the Crimson Sun

Aoteru Misumi is a young man living in the countryside of Ehime, Yamato. Working as an agricultural officer, he lives a quiet life with his wife, Saki. One day, they are visited by a horseback procession fit for a king. The most extravagant horse-drawn carriage in this procession carries none other than Denki Taira, the lord of home affairs and true ruler of Yamato.

Having lost the love of his life, Aoteru is determined to fulfill the promise he made to her of creating a peaceful world. He travels to Osaka to take the exam given by Borderland General Mitsuhide Ryumon in the hopes of serving under him. Upon arriving, he finds a cheap hotel to stay in. But Aoteru will find no rest there, as he immediately encounters a certain individual.

Aoteru and Yoshitsune Asama take the Toryumon, an employment exam required to work under Ryumon. The conditions for passing are simple: the examinees must bring him to his knees. It seems that knowledge of the art of war alone will not be enough. They will also need their resourcefulness to get through this trial.

Three years after passing the Toryumon, Aoteru is working hard under Ryumon to perform his duties to their fullest. Meanwhile, Yamato sends a demand for unconditional surrender to the neighboring nation of Seii, which has been unstable due to the harsh winter conditions. In Seii, the embers of rebellion are quietly stoked.

A new dictatorship comes to power in Seii when Ohga Wajima suggests subduing Yamato by force. She establishes her administration overnight, declaring her resolve across the land. Ohga quickly captures the hearts of her people with her charm and political prowess, and within Seii, momentum grows to launch a campaign against Yamato.

Tonotsugu Taira, Denki Taira's heir, is ordered by Fuji III, the emperor of Yamato, to go to Kanazawa with the Borderland General Corps' Right Lieutenant General, Goh Sugoh. While Tonotsugu is optimistic about this opportunity, Sugoh harbors concerns that it is a trap set by Seii.

When Seii invades Kuzuryu Castle, tensions between Seii and Yamato come to a head. Sensing something strange about the situation, the Yamato army led by Ryumon decide to halt their advance. Meanwhile, having gone ahead, Tonotsugu's men enter Seii without knowing that war has broken out, and are given a warm welcome by Muuton Nagao.