Spirit Detective Saga
Yusuke Urameshi was 14 years of age in the beginning of Yu-Yu-Hakusho, is the toughest member of his middle school and is the rival of Kazuma Kuwabara. He is a stereotypical bad kid, with a bad attendance record and picks fights with other kids at school. In the manga, he also smokes, gambles and drinks.
While skipping school and being berated by his mother, Yusuke loafs around the town. Yusuke entertains a child by making silly faces, but when the kid wanders into the street in front of an oncoming car, Yusuke shoves him out of the way. He is struck by the car, and killed.As a ghost, Yusuke is greeted by an atypical version of the Grim Reaper; a bubbly, cheerful young woman named Botan. She informs Yusuke that no one in Spirit World had expected him to die risking his life to save the little boy. Thus, they have no place for him in the afterlife. She remarks that Yusuke can return to life, but he initially declines.
Yusuke's mind changes after he attends his wake, where people he knows pay their condolences to his mother. Atsuko, his mother, is extremely distraught, borderline catatonic, about losing her son. Keiko Yukimura (his classmate) sobs uncontrollably, yelling Yusuke's name. Kuwabara appears, angry and upset that Yusuke died before they could finish their battles. When two of Yusuke's teachers belittle him at the wake, Mr. Takenaka, another teacher, berates them for insulting him. He pays his respects to Atsuko and sobs at Yusuke's passing; only then, Atsuko reacts, collapsing in tears at the mention of Yusuke. Lastly, the child whom Yusuke saved and his mother show up, and when the child asks if he can play again with Yusuke, his mother cries and hugs him. Understanding that he meant more to others than they let on, he decides to come back.
Yusuke is given an egg by Koenma, acting lord of Spirit World (in place of his father, who often left to work in other places), and is told that it will hatch a Spirit Beast, which will help him get back to life. However, he must be a genuinely good person. If he is evil, the beast will devour him. While in the anime Yusuke only accomplishes two good deeds, he does a lot more in the manga due to the timeline of events being more stretched out in the manga. This includes helping a boy Shouta get over his dog's death, helping a girl who had died get over her obsession with a boy who didn't really care for her so she can move on, and also being temporarily revived to keep his body fresh so it won't die out and not allowing Keiko know about this, though Kuwabara encounters him and Yusuke explains to him what is happening before he returns to being a ghost. Yusuke sacrifices the beast to save Keiko, who had received dreams and messages from Yusuke's ghost that he would be returning to life, and she needed to take care of his body so that he would be able to return to it. However, a fire starts in Yusuke's home and his body runs the risk of being incinerated. Keiko runs into the fire to protect it, and is trapped in the fire. Yusuke gave up all the power gained from his good deeds after his death to have Koenma save her. Koenma used this to put out some of the flames and opened up a path for her to escape from the fire.
Due to this incident, with Koenma directly in contact with Yusuke's soul, he figured that the wave cycle of Yusuke's power is extremely long and has to meet the right time to be resurrected or he would have to wait for another fifty-two years (fifty years in the Japanese version and English manga) before the next chance and decided to let Yusuke return to life earlier even though the fire incident should have delayed the process since his power gained from good deeds were used up (In the manga, Yusuke had to go through one more good deed to be eligible for this by possessing an old acquaintance named Matsuo Suekichi to help him gain the confidence to achieve his dream of becoming a boxer). The only way for Yusuke to be resurrected is by a kiss from someone who is very close to him until midnight. Yusuke could tell, by dream, to three people he knew in order to do this, but he only told Keiko and Kuwabara since his mother started drinking and would not go to bed. Kuwabara did not believe the dream, due to its awkward subject matter, and Keiko got delayed by her mother's illness. Botan possessed Keiko's mother to leave a message saying Yusuke was in a more dire state than she was. Keiko manages to kiss Yusuke in time, and Yusuke is returned.
After returning, Yusuke is surprised to notice a demon inhabiting the body of a street punk. Botan shows up and tells Yusuke that his experience with death allowed him to do these things. He is to become Earth's Spirit Detective, and protect the human race from demons.
Artifact Recovery Arc
Yusuke engages in many difficult trials in his first assignments as Detective. The first is to recover three stolen artifacts from Spirit World. Koenma trains him by teaching him how to fire his spirit energy, energy possessed by humans and spirits, as a weapon. This is Yusuke's signature attack, the Spirit Gun. Yusuke attempts to combat these three thieves: Hiei, who stole the Sword of Shadows; Kurama, who stole a mirror called the Forlorn Hope; and Goki, who stole a soul-stealing article called the Orb of Baast. Yusuke was able to defeat Gouki with the aid of Botan and his Spirit Gun. Kurama willingly turns over the Forlorn Hope, as he only wanted to use its power to save his mother's life. Kurama intended to sacrifice his life for the mirror to save hers, but Yusuke selflessly asked the mirror to take his so Kurama can enjoy his mother's life. The mirror granted Kurama's wish, taking half of each of their lives, but killing neither, and Yusuke took the mirror. Yusuke and Botan then went to fight Hiei, who kidnapped Keiko and tried to turn her into a demon. While Botan staved off the transformation, Yusuke fought the extremely-fast demon, and managed to defeat him by reflecting his Spirit Gun off of the Forlorn Hope, intentionally missing Hiei to strike it and causing the arrogant demon to believe Yusuke missed.
Yusuke then was sent to the compound of Master Genkai, an aged fighter who was looking for a successor to her powerful Spirit Wave technique (Reikō Hadō Ken or Spirit Light Wave Fist in the original Japanese version). Botan warned that a demon named Rando would probably try to inherit her technique. Yusuke fought through her tournament and defeated Rando in the end (out of luck), becoming her successor. For the next two weeks (in the Japanese anime, it is a month and in the English anime, it is six months), Yusuke undergoes tough training with Genkai. As a result, his strength radically heightens, push him from a D-class to a C-class.
Saint Beasts Arc
Yusuke was then sent to Maze Castle to defeat the four Saint Beasts and stop them from taking over the human race with demon parasites. Kuwabara decided to go with Yusuke, and Koenma sent Kurama and Hiei, who were on probation in the human world, to assist. Yusuke fought his way to Suzaku, the leader of the group, and managed to defeat him, but at the cost of his own life energy. Kuwabara, the only human of the group, saved him by transferring part of his own life energy.
Yukina Rescue Arc
Yusuke then goes with Kuwabara (and Botan in the anime) to rescue a beautiful ice apparition named Yukina, of whom Kuwabara becomes smitten. However, Yukina is actually Hiei's twin sister, a fact that Kuwabara and even Yukina herself is unaware of. Yusuke fights all the way to the Toguro brothers. Yusuke and Kuwabara defeat them with teamwork and rescue the maiden, but it turns out that the Toguros threw the fight on purpose. The younger Toguro brother coerces Yusuke to join the Dark Tournament (Ankoku Būtsukai or Black Martial Arts Tournament in the original Japanese) and defeat him in a real fight.
Dark Tournament Saga
To prepare for the Dark Tournament, Yusuke trains with Genkai for two months, moving him from a middle C class to an upper C class. Afterwards, Yusuke, Kuwabara, Kurama, and Hiei, along with Genkai as 'The Masked Fighter', enter the Dark Tournament as the guest team, Team Urameshi. Often at times barely escaping out of the fights alive, and despite heavy bias against them by the tournament committee, they fight their way to the final of the tournament to face Team Toguro.
During the semis, Genkai transfers most of her Spirit Energy through the Spirit Wave Orb so Yusuke can stand a chance against Younger Toguro, moving him from a lower B class to a middle B class. Before the finals begin, Genkai and Toguro face off in an attempt to kill one another. It is revealed that Toguro was Genkai's partner from a previous tournament. After suffering a mortal wound, Genkai, with the last of her strength, explains that when they won the tournament fifty years ago, Toguro, who was once human, had his body become a demon's in order to preserve his strength and youth. Before dying, Genkai warns Yusuke not to become like Toguro. Yusuke becomes furious with Toguro over his master's death and vows to defeat him. In the finals, Yusuke now faces Toguro. However after Toguro reveals his full power, Yusuke cannot face him and, in order to bring out Yusuke's hidden power, Toguro kills Kuwabara. This brings Yusuke from a middle B to an upper B. Yusuke prepares his final spirit gun while Toguro undergoes another power up, bringing him from what was actually about 85% of his strength to 100% of his strength. After unleashing their attacks, Yusuke comes out on top. It is revealed that Kuwabara faked his death to bring out Yusuke's power. Before they leave the island, Koenma revives Genkai.
Chapter Black Saga
In the Chapter Black Saga, Yusuke must stop Shinobu Sensui from opening a gate to demon world while defeating six other humans with newly awakened psychic powers. When he realizes he cannot defeat Sensui's true self, only possessing lower A class power against Sensui's low S-class power, he decides to have Sensui kill him to awake Hiei, Kurama, and Kuwabara's hidden potential. After he dies, his ancestral demonic blood resurrects him and boosts his power to lower S class demon power. It is revealed that he is a Mazoku, or a descendant of a Yōkai Clan (the Amazaku demons in the English dub), his ancestor Raizen having conceived a child with a human woman. Raizen made it so that when the stars reach a certain alignment, and his descendant is worthy of awakening, they would become a yōkai. When Yusuke died the first time, he was too weak to awaken the yokai blood within him. It was his subsequent missions afterwards, especially his fight against the younger Toguro, that wove and mended this deficiency. Hence, his death at the hands of Sensui caused him to come back as a mazoku demon, pushing him to S class power.
After this transformation, he fights Sensui in the Demon World. Even with his new demon energy he still cannot defeat Sensui, until he is then possessed by his ancestor Raizen to help control his new-found power. This causes Yusuke's body to transform yet again, gaining demonic eyes and long white hair, and bringing out his potential power, boosting him to upper S class demon power. As a result, Raizen, through Yusuke's body, kills Sensui which upsets Yusuke greatly. So much in fact, Yusuke wanted to track down Raizen over the ordeal, thinking that if he was to kill a human like Sensui, he should have been the one to make the decision, not his ancestor. Koenma informed him that the passage way to the living world and the demon world was closing. He presented Yusuke with a choice; stay in the demon world forever, or return to his home. Yusuke chose the latter in the end.
Three Kings Saga
In the Three Kings saga, Yusuke is removed from his position as Spirit Detective because he is considered too dangerous for the Human Realm. The Great Emperor Enma (King Yama in the English anime) wants Yusuke dead so that he does not become as dangerous as Sensui. In the beginning of the season Yusuke is forced to live his normal life in human world. However, he is troubled with what to make of his new identity as a demon. Koenma advices him to go to Genkai, who send him to a former spirite detectve, Kuroko Sanada. During this conversation Raizen sends three of his advisors inviting Yusuke to return to Demon World. Yusuke agrees to do so since Raizen interrupted his match against Sensui. He has everyone meet at Genkai's temple for a farewell and promises Keiko that he will return in three years time. After meeting Raizen, he learns that Raizen is dying because he needs to eat humans to survive, which he gave up after he met a female doctor who is Yusuke's ancestor. Yusuke fights him, but loses to him quite easily; then learns that Mukuro and Yomi are just as strong as the current, and weakened, Raizen.
After a year of training Yusuke, Raizen dies, but reveals to Yusuke that if he had eaten humans he would have already been the strongest yōkai. Yusuke chooses to hold a tournament, since he knows he is incapable of ruling Raizen's territory. During his match against Yomi, Yusuke suddenly realizes he has lost his purpose, and questions why he is fighting. He used to fight because as a child, he had been angry and neglected, and took out his anger by fighting. Then he became a Spirit Detective and fought powerful men such as Toguro and Sensui to save the world, although they were actually looking for someone more powerful to defeat them. Yusuke wonders whether he is now just waiting for someone to defeat him, now that his anger is gone and all he has is fighting, but Raizen's voices comes back and refreshes his mind. He remembers that he is fighting, not just to find his own identity, but for the sake of his friends as well. From this renewed strength, Yusuke discovers a new seikouki, and the fight between him and Yomi comes down to one punch. Rushing at each other, the fight would have been a tie, except that Yomi was able to continue standing because of an impromptu shout from Shura. Yusuke falls unconscious and doesn't awaken until after the tournament ends. Afterwards Yusuke leaves Makai shortly between the time after the tournament ends and before his three years are up. He then leaves for the Human World and meets up with Keiko on Genkai's beach.