YuYu Hakusho

YuYu Hakusho (幽☆遊☆白書, Yū Yū Hakusho?, or "YYH", lit. "Ghost Files" or "Poltergeist Report"). Yusuke Urameshi is a street-brawling delinquent attending the fictional Sarayashiki Junior High. His mother Atsuko, an alcoholic, had him at the age of 14 and raised Yusuke as a single mother. He is constantly in trouble in school, when he goes at all, and is targeted by many of the other local delinquents. His only apparent friend is Keiko, a girl who he has known for many years and his eventual love interest.
In an uncharacteristic act of altruism Yusuke is hit by a car and killed, saving a young boy by pushing him out of the way. His ghost is greeted by Botan, a blue haired woman who introduces herself as the pilot of the River Styx, who ferries souls to the underworld where they may be judged for the afterlife. Botan informs Yusuke that his act had caught even the Underworld by surprise and that there was no place made yet for him in either heaven or hell. Thus Koenma, son of the Underworld's ruler, offered Yusuke a chance to return to his body. After returning to life, Koenma hires Yusuke as the Underworld Detective, charging him with investigating supernatural activity within the Human World. Soon Yusuke is off on his first case, retrieving three treasures stolen from the Underworld by three demons: Hiei, Kurama and Goki. Yusuke collects the three treasures with the help of his new technique, the Rei Gun, a shot of aura energy fired mentally from his index finger. He then travels to the mountains in search of the reiki master Genkai. Together with his rival Kuwabara Yusuke fights through a tournament to become the heir to Genkai's techniques, as well as trying to find Rando, a demon who steals the techniques of martial arts masters and kills them. Yusuke defeats Rando in the final round of the tournament and trains with Genkai for several months, gaining more mastery over his aura. He is then sent to Demon city in the underworld where Kuwabara, Kurama and Hiei aid him in defeating the Four Beasts, a quartet of demons attempting to blackmail Koenma into removing the barrier keeping them out of the Human world.
Yusuke's next case sent him on a rescue mission to save Yukina, an Ice Maiden. During the rescue he meets Toguro a human turned into the strongest of demons. Toguro invites Yusuke to the Dark Tournament, an event put on by corrupt rich humans in which teams of demons, and occassionally humans, fight fierce battles for the chance to receive any wish they choose. Team Urameshi, consisting of Yusuke, Kuwabara, Kurama, Hiei and Genkai (initially disguised as the Masked Fighter), fights through the early rounds to face Team Toguro and come out on top, finding that Team Toguro's owner, Sakyo, was attempting to win prize money in order to create a large hole to the Demon Plane, but with his loss, destroys the tournament arena, killing himself in the process. Yusuke returns home, but has little time to rest as he is challenged to a fight by three teenagers who end up taking him hostage with new superhuman powers. Kuwabara and the others rescue him as they learn that the whole scenario was a test by Genkai. It is revealed that Shinobu Sensui, Yusuke's predecessor as Underworld Detective, has recruited six other powerful beings to help him take over where Sakyo left off, boring a hole to the Demon Plane. Yusuke and his friends fight Sensui's minions one by one making their way to the final fight between the two detectives. Sensui kills Yusuke then retreats into the newly opened portal to Demon World, followed by Kurama, Hiei and Kuwabara. Yusuke is reborn as a partial demon, finding out that his ancestor passed down a recessive gene that would hide until an heir with sufficient power surfaced, when his demonic lineage would be revealed. Yusuke travels to the Demon plane and defeats Sensui, aided by the spirit of his ancestor who takes control of his body to finish the fight.
As they return to Human World, Yusuke is stripped of his detective title as King Enma orders he be captured and executed, afraid his demon blood could cause him to go on a rampage in the human world. Yusuke, unhappy with having been controlled by his ancestor, Raizen, accepts an offer by Raizen's followers to go back to Demon World. It is revealed that Raizen is on the brink of death, a death that would topple the delicate balance of the three ruling powers of the Makai Realm. Hiei and Kurama are summoned by the other two rulers, Mukuro and Yomi, respectively. The three train in the Makai Realm for a year, at which time Raizen dies and Yusuke inherits his territory. Yusuke takes the initiative and proposes a tournament to name the true ruler of the Makai, which is eventually agreed upon by all. The tournament progresses, as Yusuke and Yomi meet in the 2nd elimination round where Yusuke is defeated and knocked unconscious. Yusuke awakes days later to find that the tournament was won by Raizen's old friend Enki. Yusuke stays in the Demon Plane for a while longer, but eventually returns to the Human world to be with Keiko.