Yuusuke Urameshi
Our 14-year old main character and legendary street fighter, this juvenile delinquent is one of Reikai's psychic detectives. He is rude, violent and not very bright. His intelligence seems to elevate in a fight, where he often uses his intellect to win, and he always wins. He also has a special trademark ability, using the Reigan, which is firing energy from his finger like a shotgun. A surprising change occurs in Yuusuke's later life, when he dies again; but this time he resurrects automatically, but as a demon. It happens that the gene from his demon ancestor of centuries ago, suddenly showed itself up and turned him into a demon. Despite the change he is still the same old person, though.
Youko Kurama
Kurama is a bishounen, which would be gross in real life but these sort of characters are often very popular in Manga and Anime. They are stereotypically quiet, studious, extremely intelligent and polite, which is exactly what Kurama is. Kurama is actually a 1,000 year-old Youko, a fox demon who terrorized Makai as the leader of a gang of robbers back then. 15 years ago he was pursued and heavily injured by a Reikai detective, and travelling to Ningenkai as a soul, he took over the body of an unborn baby and was reborn in a human body. Known as Minamino Shuichi in Ningenkai, he leads a normal life and loves his human mother dearly for raising him. Kurama was given the power to transform back to his Youko self during a fighting tournament.
Botan
One of the denizens from Reikai, she transports souls to and from Reikai. She accompanied Yuusuke when he was a ghost, and when he was reincarnated she assumed an identity in Ningenkai and acted as Yuusuke's secretary and assistant. She doesn't do much though, her abilities being healing and running errands.