Karao Saeki's father was the father of Karao Saeki. He raised Karao by himself until he was killed by his own son.
He was a very large and intimidating looking man who looked rather unkept. He kept his pale hair slicked back and sparse hair on a large chin.
Karao Saeki's father was an abusive and domineering man who kept Karao under his thumb. He had little regard for the lives of others, even his own family. He would go as far as either sacrifice or threaten to sacrifice his relatives for his benefit.
Karao told his past to Tooru Mutsuki where recounted his father as cruel and belittling person. He killed Karao's mother because he could not find food, then raised his son alone as far away from society as possible. One day, he left home and disappeared for over a month neglecting Karao. Some time after he returned, he found out that Karao had been interacting with humans and angered, injured his son before abandoning him. However, he returned that night after Karao had gone to sleep and killed Minomi, a friend of Karao who was spending the night in the tent they lived in. He was killed by Karao afterwards.
He verbally and physically abused his son and made it clear that he prioritized his own life over Karao's. He considered Karao as lacking in intelligence, so they lived in the mountains away from society as Karao's father feared his son would mess up and bring attention to him. As he kept his son isolated and fearful of him, he enforced strict rules and would leave him alone for weeks at a time. His behavior and actions deeply effected Karao and contributed to his disturbing behavior as an adult.