Kai (启 Qǐ) is a street musician in Kowloon who plays the Chinese fiddle. He was a friend of Iwao Hazuki.
Later on, Ryo does the Chawan Sign at various places when trying to get into the Yellow Head building, someone gives him a sign to go to room 503 of the Moon Child Building. Once he goes there the room is dark and he sees a dark mysterious figure. The man ask him to spar with him and he does. Ryo relies on sight in the dark and the man teaches him a move called Predictive Explosion. Once the lights are turned on it is revealed that the man was Kai.
Ryo recognizes him from before, and then he opens his eyes revealing that he is not actually blind. Kai knew he was Iwao's son. He tells him that his father visited the place, they became friends and shared knowledge on martial arts moves. He asks if Iwao is well and Ryo reveals the sad truth that he was murdered by Lan Di. He is then shocked and feels terrible that his friend was killed.
He asks if there is anything he can do for Iwao. He responds that he heard that Zhu is being held captive at the Yellow Head Building and that he has something to do with his death. Kai then gives him a photo of Yuandao Duo, a scout for the Yellow Heads. He tells him to keep winning at street fights then the scout may allow him to get inside the building.
- Kai's zodiac sign is Pisces and he has a B blood type.