Yu Yu Hakusho

His ghost is greeted by Botan , a woman who introduces herself as the pilot of the Sanzu River , who ferries souls to the Underworld ( 霊界 , Reikai ; "Spirit World" in the English anime dub) 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 not yet a place made for him in either heaven or hell. Thus Koenma , son of the Underworld's ruler King Enma , offers Yusuke a chance to return to his body through a series of tests. Yusuke succeeds with the help of his friends Keiko Yukimura and Kazuma Kuwabara .

After returning to life, Koenma grants Yusuke the title of "Underworld Detective" ( 霊界探偵 , Reikai Tantei ; literal translation</span>"}]]}'>lit. ' Spirit World Detective ' , 'Spirit Detective' in the English dub) , charging him with investigating supernatural activity within the Human World ( 人間界 , Ningen Kai ) . Soon Yusuke is off on his first case, retrieving three treasures stolen from the Underworld by a gang of demons: Hiei , Kurama , and Goki. Yusuke collects the three treasures with the aid of his new technique, the Rei Gun, a shot of aura or Reiki ( 霊気 , Reiki ; literal translation</span>"}]]}'>lit.

' Spirit Energy ' ) fired mentally from his index finger. He then travels to the mountains in search of the aged, female martial arts master Genkai . Together with his rival Kuwabara, Yusuke fights through a tournament organized by Genkai to find her successor. Yusuke uses the competition as a cover to search for 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. Yusuke is then sent to Labyrinth Castle in the Demon Plane ( 魔界 , Makai ; literal translation</span>"}]]}'>lit. ' Demon World ' ) , a third world occupied solely by demons, where Kuwabara and the newly reformed Kurama and Hiei assist 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 sends him on a rescue mission, where he meets Toguro , a human turned into a demon.

To test his strength, Toguro invites Yusuke to the Dark Tournament ( 暗黒武術会 , Ankoku Bujutsukai ; literal translation</span>"}]]}'>lit. ' Dark Martial Arts Association ' ) , an event put on by corrupt, rich humans in which teams of demons, and occasionally humans, fight fierce battles for the chance to receive any wish they desire. Team Urameshi, consisting of Yusuke, Kuwabara, Kurama, Hiei, and a disguised Genkai, traverses through the strenuous early rounds to face Team Toguro in the finals and win the tournament. They learn that Team Toguro's owner, Sakyo , was attempting to win to create a large hole from the Human World to the Demon Plane and allow countless demons through.

With his loss, Sakyo destroys the tournament arena, killing himself in the process. After the tournament, Yusuke returns home but has little time to rest as he is challenged to a fight by three teenagers possessing superhuman powers who take the detective hostage. Kuwabara and the others rescue him and learn that the scenario was a test from Genkai. It is disclosed that Shinobu Sensui , Yusuke's predecessor as Underworld Detective, has recruited six other powerful beings to help him take over where Sakyo left off, opening a hole to the Demon Plane to cause genocide of the human race.

Yusuke and his friends challenge and defeat Sensui's associates individually, culminating in a final battle between the two detectives. Sensui kills Yusuke and then retreats into the newly opened portal to the Demon Plane. Yusuke is reborn as a partial demon, discovering 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 with the aid of his ancestor who takes control of Yusuke's body to finish the fight.

As they return to the Human World, Yusuke is stripped of his detective title in fear that Yusuke's demon blood could cause him to go on a rampage in the Human World. Yusuke, unsettled at having been controlled by his ancestor Raizen , accepts an offer by Raizen's followers to return to the Demon Plane. Raizen, desiring a successor to his territory, is on the brink of dying of starvation, a death that would topple the delicate political balance of the three ruling powers of the Demon Plane. The other two rulers Mukuro and Yomi summon Hiei and Kurama, respectively, to prepare for an inevitable war.

The three protagonists train in the realm for one year, during which time Raizen dies and Yusuke inherits his territory. Yusuke takes the initiative and proposes a fighting tournament to name the Demon Plane's true ruler; Mukuro and Yomi agree to Yusuke's terms. During the tournament, Yusuke and Yomi meet in the second elimination round where Yusuke is defeated. Yusuke hopes a similar competition will be held every few years to determine the Demon Plane's ruler.

Two years later, Yusuke returns to the Human World while Hiei stays with Mukuro and protects humans who have accidentally wandered into the Demon Plane. After learning that King Enma was falsifying reports on demon activity against humans in order to justify keeping the two separated, Koenma takes over his father's position and allows access between the Demon Plane and the Human World. Genkai dies and leaves her estate to the main characters. The story ends with Yusuke and his friends reuniting at a beach.