Raizen's friends are nine upper S Class demons who used to have friendly fights with Raizen regularly, thousands of years before the show, before they shunned him for refusing to eat humans over a Human woman. One of them, Kokou, was in love with Raizen, but resented him after he "cheated" on her with the woman who became Yusuke's ancestor. Sometime later, she married Enki, another one of Raizen's old sparring pals. Despite this, without Raizen, they lost the will to fight, and became out of practice for hundreds of years. After Raizen's death, they all went to pay their respects, at his grave. Despite abandoning him, every one of them regretted his passing.
They were all very successful in the Makai Tournament, because of their powers, which nearly rivaled those of the Three Kings themselves. Bar one, all of the finalists were Raizen's friends. This is whom most of them lost to:
Kokou (弧光): Lost to Kujou in the fourth round.
Enki (煙鬼): Champion of the D-block, went on to defeat Saizou and win the tournament.
Kujou (九浄): Champion of the B-block, lost to Saizou in the semi-finals.
Natsume (棗): Lost to Mukuro in the third round.
Saizou (才蔵): Champion of the A-block, lost to Enki in the final round.
Tetsuzan (鉄山): Lost to Saizou in round two.
Souketsu (痩傑): Defeated Shu in round two, and was defeated thereafter.
Shu (周): Defeated by Souketsu in round two.
Den-Hou (電鳳): Lost to someone, before the fifth round. (Most likely to Enki)
After the tournament had ended and Enki became the ruler of the Makai, all of Raizen's friends went their separate ways, save Kokou/Enki and Natsume/Kujou.
- Shu's height in the anime is far greater than in the manga, where he is easily the shortest of Raizen's friends.
- It was hinted that Raizen's friends in the past were stronger than Yomi and Mukuro, as Enki stated that they were rusty because they didn't train or fight for a long time.