Soga Seikan (1592-?) was a samurai from Joseon who served Nakagawa Hidenari, the first daimyō of Oka as a retainer. He was born in 1592 in Joseon. Hidenari participated in the Imjin war. In 1597, he heard crying near his camp in Suwon, and his retainer found a child by the river. The child looked so friendly that Hidenari invited him to join them. A prisoner told them that the child was the son of 曾清官 (Zeng Qing Guan), commanding officer of Joseon who led 500 soldiers, but the child's name was still unknown. Hidenari pitied the child and decided to raise him in the camp, naming him Seikan (清官), using the same character of his father.