Sozen U. Kozui, also known as The Traveller and The Battle Sage, is the Sixth Emperor (Imperator Sextus) of the Empire.
He was the adoptive father of Ijuiin Kokoda.
He wielded the Aoge's Earth Control (VIII).
Sozen Umiya Kozui was born in the relatively wealthy city of Daleworth, the Republic. Upon attending school he realised his ability to sense Ge was significantly higher than his peers, however limited use of it in fear of being taken in to the Republic Army and trained to be a soldier. As a result of this he graduated as a farmer, opting to live a peaceful life instead of one plagued by war. Even when his wife was executed by military soldiers he refused to allow his anger to drive him to war, as he believed that his part in any battle would only drive violence forward.
One day, upon visiting the Crimson Palace, he encountered Waru the Bloodking and was instantly fearful of the evil power within him. Upon learning that the country was to go to war and that Waru was one of the Holy Knights, Sozen became distressed and abandoned his home to live as a Sage on the Sage Islands. He spoke to many of the Sages about the extent of the Bloodking's power yet the Sages affirmed that they would not become involved in the conflicts of the world as they had removed themselves from it. Sozen was furious at the ignorance of the Sages, that they would not use their great knowledge and power to attempt to bring peace. Despite earning the title of Sage, he defected from the islands and began a great pilgrimage across the Wasteland to find a power capable of immobilising the Bloodking. Whilst on this journey he discovered the abandoned Ijuiin Kokoda near death. He spent time nursing him to health, including allowing the child to feed off his arm to survive. He also visited the many different clans of the Wasteland and offered healing and medical assistance to those in need of it. In return, they would teach him their ways of life and principles. Unfortunately, although he had come across many powerful individuals in the Wasteland, none had a Ge that could rival that of the Bloodking's.
He arrived in the Empire by following the flow of Ge and was instantly arrested for being a trespasser. He was taken to the Emperor Quintus, who marvelled at his ability to navigate the Wasteland and the Great Forest. The great power of the Emperor's Ge brought great joy to Sozen, and he told Quintus of the terror of the Bloodking. Quintus, however, told Sozen of his affliction that would take his life soon. Sozen wept that he could not find anybody capable of neutralising this evil on his travels and lamented that the Bloodking would eventually take control of the world. It was at this point that Quintus, who was blind and also had a great sense of Ge, said to Sozen: "Your own Ge is beyond any I have ever seen, even my own. You have been blinded by fear, yet even though I myself am blind I see this. It can only be you that ends this Bloodking." He immediately named Sozen his successor, much to the shock of his subjects.
He was later appointed Emperor and lead the country during the War for the Wasteland. He fought the Bloodking to the death, and named Ken Tanaka as his successor in his dying words.
He named Ken Tanaka, Leo Nekota and Genbu Akasha as his Masters.