Kōyū is dedicated to serving his foster father, though he often feels that Reishin had only adopted him on whim and he was unworthy of being given the Hong name. In the anime, Reishin is depicted as adopting Kōyū from the streets, apparently impressed by Kōyū's ability to run a lottery with various prizes. The novels illustrate a much darker past for Kōyū, where he had been orphaned as a baby and adopted by a loving elderly couple, who named him "". However, the couple was killed by bandits and Kou had been forced to live as a slave before being abandoned as a sacrifice to stop a flood. Reishin found him at this point and saved him, telling the child that his reasons were so Kou could care for Yuri-hime, who had fallen ill. As Kou and Yuri recovered at the Hong manor, Yuri tricked him into believing the Hong manor was haunted so he would not escape. To further the deception, she arranged for the furniture to be rearranged all the time so that he would always become lost, which eventually resulted in Kōyū lacking any sense of direction. Reishin eventually formally adopted Kou, taking care to rename the child "Kōyū Ri" in hopes that Kōyū could live as he wanted without the responsibilities of Hong clan to burden him.