Itsuki

Itsuki is composed, philosophical and intensely fascinated by Sensui. His attachment is not based on sharing Sensui's original moral beliefs; he is captivated by Sensui's contradictions and by the gradual deterioration of a person who once divided good and evil into absolute categories.

He admits that he deliberately watched Sensui become psychologically darker rather than trying to save him. Itsuki understands this fascination is selfish and disturbing, yet makes no attempt to present it as noble.

His outward calm rarely breaks even when confronting Yusuke's allies. He prefers observing and manipulating circumstances from another dimension to direct physical combat.

Itsuki belongs to the Yaminade, a rare demon species capable of moving through dimensional boundaries. His abilities allow him to create and manipulate passages between spaces, making him uniquely suited to maintaining the tunnel to Demon World.

He controls a dimensional creature known as the Reverse Man, within whose body an isolated subspace exists. Itsuki can use it to imprison targets and observe events occurring outside.

His powers are primarily spatial rather than offensive, but they allow him to restrain opponents who possess far greater conventional fighting strength.

Itsuki first encountered Sensui while Sensui was still working as Spirit Detective. Sensui defeated him and prepared to kill him, but allowed him a final request. Itsuki asked to live long enough to watch the final episode of a television program they both happened to follow, and the absurdly ordinary request intrigued Sensui enough to spare him.

Itsuki subsequently accompanied Sensui and became his confidant. He was present during the period in which Sensui discovered humans torturing demons at the Feast of Human Vices and watched his worldview collapse. Rather than steering him away from his increasingly destructive path, Itsuki became fascinated by the change.

During the Chapter Black conflict, Itsuki maintains the dimensional gateway and uses the Reverse Man to imprison Kuwabara, Kurama, Hiei and Koenma while Sensui fights Yusuke. After Sensui's defeat, Itsuki takes his body into an isolated dimension so that Spirit World cannot claim it.

Shinobu Sensui is the center of Itsuki's life. Itsuki serves as his closest companion and openly expresses an obsessive attachment to every aspect of his personality.

Yusuke Urameshi opposes Sensui's plan and becomes the opponent whose battle Itsuki watches from the Reverse Man.

Kazuma Kuwabara possesses the dimensional cutting ability required to complete Sensui's plan.

Kurama, Hiei and Koenma are imprisoned with Kuwabara inside Itsuki's dimensional creature during the final confrontation.