Eight season of Yao Shen Ji.

Yusuke Urameshi is not exactly what you'd call an angel. In fact, some might call him down right devilish. But when he dies in an accident trying to save a child, he finds himself in the Spirit World. Unfortunately for Yusuke, his name is not listed in the Book of Enma, which means it was one big mistake! So he should return from the Spirit World, but must pass a few tests first, and become a detective of the spiritual world. So now Yusuke works in the Spirit World as a half-dead, half-alive agent for Koenma, son of the ruler of the Spirit World. This position does have its disadvantages, especially when you're trying to enjoy your summer vacation and Koenma gets kidnapped! So now Yusuke must interrupt his summer fun to find Koenma and trade the Golden Seal of King Enma for his life. But if someone other then King Enma has the Golden Seal there will be chaos in the Spirit World! What's a half-dead spirit detective to do? With the aide of his closest allies, Yusuke sets off for Magma Valley, to save the life of the one who saved his, and find out who's at the bottom of this evil conspiracy. (Source: AnimeNfo)

Millennia ago, a war was fought between the Netherworld and the Spirit World. Ultimately, the Netherworld was destroyed and Lord Yakumo, the King of the Netherworld, was banished to the depths of space. Now, five defenders from the Spirit World must team-up against Yakumo's Demon-Gods for possession of five, mystical sites. But Lord Yakumo is dangerously close to reclaiming the Power Sphere—the source of the Netherworld's energy—and once it is again in his possession, our world will become the new Netherworld. (Source: AniDB)

One fateful day, Yuusuke Urameshi, a 14-year-old delinquent with a dim future, gets a miraculous chance to turn it all around when he throws himself in front of a moving car to save a young boy. His ultimate sacrifice is so out of character that the authorities of the spirit realm are not yet prepared to let him pass on. Koenma, heir to the throne of the spirit realm, offers Yuusuke an opportunity to regain his life through completion of a series of tasks. With the guidance of the death god Botan, he is to thwart evil presences on Earth as a Spirit Detective. To help him on his venture, Yuusuke enlists ex-rival Kazuma Kuwabara, and two demons, Hiei and Kurama, who have criminal pasts. Together, they train and battle against enemies who would threaten humanity's very existence.