
Name: Mitarai Kiyoshi
Race: Human
Hair: Blond
Eyes: Blue
Age: 14
Born: February 10
Blood Type: A
Lives with parents and older sister.
Mitarai had always been pushed around at school due to his weak character. Thus it would explain how easily he had joined Sensui's side after viewing the video, Chapter Black, since the boy had already experieced abuse by his own kind. He earns the nickname "Seaman" for his ability to create a dimension made of water and beasts of water by simply combining his blood with any kind of liquid nearby. The more he blood he adds, the bigger the monster. The more moisture, the easier it spreads.
The confrontation with Kuwabara made Mitarai question his opinion on humans. He believes in the dark side of humanity yet the kindness he experiences after Kuwabara refused to kill him confuses him. Troubled evenmore after Botan pushed him out of the path of a falling bookcase, Mitarai eventually decides to help save Ningenkai/Human World from the youkai that could be unleashed after the tunnel to Makai/Demon World opens. Which turns out to an advantage to Yusuke and the others to have a man from the inside.
Throughout the Sensui saga, Mitarai starts to show his inner strength. This change shows greatly after he defeats the first game in Amanuma's territory, letting the boy know that he had chosen the right side entirely on his own. The second change is when the leader of the Spirit Defense Force claims that it would be better to destroy Yusuke to stop his demon blood from awakening. Mitarai threatens that it would happen over his dead body and proceeds to make a speech about it doesn't matter who you are but what is in your heart.
Afterwards, Mitarai's role is over in the story and he returns to a better life.