Urameshi Yusuke: after he dies tring to save the life of a kid playing in the middle of a busy intersection he is given another chance to redeem himself as a sprit detective.
Kuwabara Kazuma: Once the enemy of yusake becomes his side kick after helping yusuke out more than once. He does develope his own sprit powers like his phycic abilities and a sprit sword.
Kurama: Previously a steathy demon fox now has change into a warm and lovable "human". But he is not with out the his trusty rose wip which can cut through just about any thing.
Hiei: Bad Boy Supreme. Incredibly fast and incredibly powerful. He's got a wicked when it comes to insults toward Kuwabara but don't get him wrong he really does have a soft spot for his team members.
Botan:Also know as the Angle of death, is Yusuke's guide in the after life and as a sprit detective.
Koenma:The son of the big boss up stair who chooses to take the form of a toddler... no that thing doesn't come out of his mouth.
Genkai: Affectionately called, old lady, by Yusuke, returns to her youth full self when at the peak of gathering her energy. She trains Yusuke to become even more powerful.
Keiko:One of Yusuke's "school mates". She brings him back to the world of the living when she kisses him. Ooooo la la.
Yukina:The long lost sister of Hiei and the love interest of Kuabara she is the only one who calls him by his first name Kazuma. She is also an Ice apparition with ability to heal which comes in handy