The Demon World Tournament (魔界武道会 Makai budōkai?) was created and sponsored by Yusuke Urameshi as an alternative to the all-out war predicted to occur after the death of Raizen, one of the three great powers of Demon World. The conditions are: first, that anyone can participate; then, that they all leave all former kingdoms attachmenents; and finally, that the winner of the tournament gains absolute power over Demon World, and can do as he or she pleases for three years and all the Demon World inhabitants must abide the winner's bidding.
The tournament took place in Gandara, the former kingdom of Yomi.
All of the matches occurred on top of Okunenju, gargantuan trees of the Demon World. At least one, or possibly all, of these were planted by Yoko Kurama several thousand years before the start of the tournament. As a result, he was able to manipulate the roots during his match with Shigure.
It took all of 12 hours for word of the tournament to spread throughout the known parts of Demon World. However, it was proposed by Yomi that the tournament not begin for 100 days after it was announced, to which Yusuke and Mukuro agreed. A total of 6,272 demons signed up for the tournament. As a result, the preliminary matches consisted of 128 fights with 49 demons, in which the last person standing in each group progressed to the first round of the tournament. Each preliminary battle takes place on a gargantuan Okunen Tree.
In the manga, winners of each group were determined by the collection of special rings placed around the neck of each fighter. In order to remove the ring, a fighter would have to either force the opponent to reveal their secret code or decapitate them. Yusuke, instead of retrieving the rings, merely knocked every one of his opponents off of the platform, automatically disqualifying all of them.
- Seitei, to Hokushin
- Touou, to Hokushin
- Chu, to Natsume
- Shura, to Yomi
- Koryu, to Shishiwakamaru
- Shishiwakamaru, to Hokushin
- Touya, to Kujou
- Hokushin, to Kokou
The main matches of the tournament take place on man-made arenas divided into multiple sections: mountain, jungle, plains, desert, and lake. These different types of terrain were designed to give the combatants the chance to take the fight to an area most suited to their fighting style and abilities.
The 128 winners of the preliminary round then competed in a standard single-elimination tournament. Each fighter was placed into one of four blocks: A, B, C, or D. Due to the unique nature of each fight, the length of every fight, and thus every round, was different for all four groups.
- Nekobaba, to Yusuke (shown in the anime; mentioned in the manga)
- Zakuro, to Toboso (manga only)
- Rinku, to Sasuga
- Shigure, to Kurama (shown only in the anime)
- Shishiwakamaru, to Hokushin (anime only)
- Jin, to Souketsu (anime only)
- Suzuki, to Kagura (the one who defeated Suzuki wasn't mentioned in the anime, though Suzuki's defeat wasn't mentioned at all in the manga)
- Touya, to Kujou (anime only)
- Natsume, to Mukuro (this loss occurred in the third round in the anime)
- Hiei, to Mukuro (this loss occurred in the second round in the anime)
- Yusuke, to Yomi (this battle endured 60 hours in the manga)
- Kurama, to Kujou
- Yomi, to Enki (in the anime this happens in the fifth round, in the manga his defeat is against Kokou)
- Kokou, to Kujou (quarterfinals)
- Kujou, to Saizou (semifinals)
- Saizou, to Enki (finals)
- Mukuro, to Enki (in the anime, her loss occurred in the semifinals)
As a result of the final rounds, the winner of the First Demon World Tournament was Enki.
There were 6272 participants in the Demon World Tournament:
- Nekobaba - A cat demon that can extend his claws and grow in size in the anime. Named Nekotama in the anime. Defeated easily by Yusuke.
- Zakuro - An arrogant demon who gloated to Yusuke that he would win the tournament (first by defeating him, then Yomi) and engulf Demon World with darkness, only to be defeated in the first round by a no-name demon. He makes a cameo in the anime in Hiei's patrol group.
- Koryu - An armored demon with a shell so strong that it is unharmed by the Banshee Shriek. Tried to eat Shishiwakamaru with the mouth on its back, but was torn open from the inside by Shishi's true form.
- Ojaku - A flying, gelatinous demon that tried to chase after Jin, but was destroyed by electric shocks from the Tornado Fist Explosion.
- Sasuga/Kotei - a demon girl who Rinku falls for. Defeated Rinku, but lost in the second or third round (possibly to Mukuro).
- Kagura - all that is known about this demon is that Suzuki "didn't stand a chance" against her.