Kai (known as Ryo in the anime) was a human and a student underneath the martial arts master Mitamura, as well as a former member of Team Ichigaki during the Dark Tournament Saga, where he was brainwashed by Dr. Ichigaki and referred to as M-2. He is now an ally of Yusuke Urameshi during the Dark Tournament finals in the Dark Tournament Saga. He was called Chris in the Filipino dub of the anime. He was voiced by Tarō Arakawa in the Japanese version and by Kyle Hebert in the English dub.
Kai was an older-looking man with a braided ponytail and a mustache who appeared to have been of Chinese descent. He wears a Chinese Mandarin-style pink buttoned cheongsam with yellow lines, pants, and black shoes.
Kai, along with En and Ryo, were students under the martial artist master Mitamura. At one point in time, Mitamura contracted some sort of disease. Not having the 7 million necessary to treat him, the students were helpless until they were approached by Dr. Ichigaki. Ichigaki promised to cure him for free in exchange for them being guinea pigs in his scientific experiments. However, unbeknownst to them, Dr. Ichigaki's true purpose was to brainwash them and use them as mindless slaves to fight for him.
Dark Tournament Saga
He made his debut alongside the rest of his Team in the Dark Tournament, facing and killing a member of an unnamed team in the early rounds of the tournament. Alongside En and Ryo, he partook in a 3-on-3 battle royal against Yusuke, Kuwabara, and then-masked Genkai. In the anime, the three brainwashed students' teamwork is flawless, putting pressure on Team Urameshi and soundly landing blows on them (this is not the case in the manga). The trio would come to cause severe damage to Kuwabara, who refused to kill them since he knew they were innocent humans (before the actual fight, Kuwabara had a dream about their ordeal). Ultimately, his & his teammates' lives were spared when they were returned to normal by Genkai's energy attack, finally freeing them from Dr. Ichigaki's control. He & his teammates had a tearful reunion with their master, who had been healed by Kurama.
He also appears alongside En, Ryo, and Mitamura during the final battle between Teams Urameshi and Toguro as part of the audience since M2, M1, and M3 are now allies of Yusuke. In the manga, his soul starts to be awoken by Younger Toguro's soul absorption technique for consumption, much to the horrible shock of both En and Ryo. Whether he actually dies from this is unknown.
- Ryo's overall appearance greatly resembles fighting game series Virtua Fighter character Lau Chan (mostly in the first games). He vaguely resembles Dragon Ball character Mercenary Tao and Mobile Fighter G Gundam character Master Asia as well.
- In the manga, he is called “Kai” while in the anime they say “Ryo”. Back during Round 2 of the tournament, it was established that these three guys are named “Kai”, “Ryo”, and “En”, but it wasn’t clearly established who was who aside from Kai. Most likely, the anime decided back then that Ryo was the one with the staff, and decided to stick with that in spite of the manga. The Spirit World Who’s Who guidebook identifies “Kai” as the one with the staff (in keeping with the manga version), “En” as the one with the throwing discs, and “Ryo” as the one with the claw attack.
- The subtitles call Kai’s staff attack “Swing Crush” in the Japanese version of episode 33, but in episode 35 it’s “Swing Crash”.
- Despite not haven known about Urameshi at all (like M1) until the Dark Tournament's Finals episodes of the Dark Tournament Saga, M-2 was an ally of Yusuke, supporting and cheering for Team Urameshi.