Rei ("Ray" in Viz's English manga) is the successor of Nanto Suichouken, which is said to be the most elegant of the Nanto Seiken styles. He represents the "Star of Justice". Rei is introduced in the manga as a ruthless chauvinistic mercenary-for-hire of shifting allegiance whose sole purpose is to kill "the man with seven scars," whom he believes was responsible for kidnapping his sister Airi. Rei is hired alongside Kenshiro by Mamiya to protect her village against the Fang Clan. After Airi is found and rescued by Ken, Rei becomes Kenshiro's closest ally and supports him for a few story arcs.

During an assault on the village, Rei challenges Raoh in Kenshiro's honour but is easily defeated by a technique giving him only three excruciating days to live. With the help of Toki's Hokuto Shinken, Rei's life is extended and his hair turns brilliant white. He uses his final moments to avenge Mamiya, who was once tortured by his Nanto Kōkakuken rival, Yuda. Shortly afterwards, Rei dies an off-screen death. In the 1986 movie, Rei again challenges Raoh but this time his death is almost instantaneous.

(Source: Wikipedia)