Kaio Retsu

Height: 176 cm (5'9")
Weight: 106 kg (233 lbs)
Fighting style: Byakurin Temple Chinese Kenpo
Retsu Kaiou was a man of robust build, with long, black hair tied in a single braid. His eyebrows were somewhat bushy, resembling small scythes. In combat, Retsu usually wore dark blue or black Shaolin monk's trousers and boots, without a shirt. However, he could occasionally dress elegantly or casually.

Retsu is also notable for possessing a "fighting spirit" that can control his body even when he has lost consciousness or the will to fight, protecting himself and his knowledge of Chinese martial arts. This spirit is notably manifested during his fight with Pickle, moving Retsu's body to counter Pickle's attack, despite Retsu having sworn to abandon the "useless" kenpo after his earlier mental breakdown. This spirit also helped Retsu recover from Musashi Miyamoto's attacks, even though Retsu briefly lost consciousness. According to Yuujirou Hanma, Retsu's own fighting spirit was able to awaken the "Hanma spirit" in Baki Hanma.

From the very first installment of the franchise, Kaiou Retsu has strived to become ever more powerful, even practicing non-Chinese martial arts. He subsequently established himself as the second strongest in China, right after Kaiou Kaku, until his death at the hands of Musashi. Even after that, Retsu continues to fight posthumously as a right arm attached to Katsumi Orochi's body. Retsu's "spirit" is able to control him at will and even allowed Katsumi to use his kenpo technique. He has proven to be incredibly stealthy, as he was able to avoid detection while infiltrating the base where Pickle is located by walking extremely close to one of the guards.

Retsu was an accomplished fighter who reached the rank of Kaiou, strong enough to defeat Mount Toba in under a minute and Katsumi with a single punch. In fact, his punch was so powerful that it permanently damaged Dorian's brain, reducing his mentality to that of a child. His most impressive feat was turning a rock into a perfect sphere using only his bare hands. During his battle with the convict Hector Doyle, Retsu also proved highly skilled with a wide variety of weapons, from throwing knives and ropes to nine-section whips and even a dao. Retsu's fighting style is the Chinese Kenpo of Byakurin Temple (白林寺, Byakurin-ji).

Retsu sometimes resorts to dirty tactics, such as using his hair to blind his opponent, setting them on fire with alcohol, or using his shirt to launch dirt as projectiles. On one occasion, Retsu used "Mushin," a mental state in which he automatically uses his techniques and reflexes to defend himself and fight. Despite this, he was defeated by Pickle's brute strength, and even collapsed in despair upon realizing that his technique was useless against him.

Born in a Chinese temple, Retsu was trained to be the heir to the Chinese Kenpo style. A man of great discipline and skill, he swore to uphold the honor and pride of the ancient art of Chinese Kenpo. However, over time, Retsu learned to appreciate the diversity of fighting styles from around the world, rather than claiming that Chinese Kenpo was the strongest, as he had done for most of the Ultimate Tournament. Despite his deep knowledge of his style, he was initially unwilling to learn from other disciplines. But after befriending Katsumi Orochi after the tournament, he seemed eager to both teach and learn at the Shinshinkai Dojo.

Retsu is an intelligent person. As a trained martial artist, both physically and mentally, Retsu Kaiou possesses a level of intellect unattainable for most ordinary people. Like other martial arts masters in the franchise, Retsu can easily decipher an opponent's fighting technique, including its usage and weaknesses.

Although he may appear very calm, Retsu is anything but patient in combat. Furthermore, throughout the story he demonstrated an overconfidence in his abilities, which, combined with his overwhelming desire to prove his strength in battle against powerful enemies, ultimately led to his death at the hands (or sword, in this case) of Musashi Miyamoto, who managed to overcome Retsu's Xiaoli defense and severed most of his internal organs, as well as his spine.

He's more uptight than the rest of Baki's friends, but sometimes he does truly absurd things, like throwing a spinning punch out of frustration. Although he was never really a bad person, he evolves from a stereotypical role model to perhaps one of the kindest and most caring people in the series. When Kaiou Dorian became mentally incapacitated, Retsu took pity on him despite everything he had done before, even promising to buy the now childlike man a mountain of candy while fighting back tears.

Retsu learned martial arts at the Byakurin Temple. During his training, he was known as Shaoron Retsu. One day, he was barred from participating in the test to obtain the title of Kaiou. This title is awarded only to the best Chinese martial artists. Retsu was locked in a cell guarded by six armed guards, but he broke free, defeated the guards, and took the Kaiou exam. Furious, Retsu demanded to know why he hadn't been allowed to participate. His master, Kaiou Ryuu, led him to the location of the great tunnel. Ryuu told him about the man who dug this tunnel in a single night, using only his fists and legs. It was later revealed that this man was Kaiou Dorian. Retsu thought he had been barred from the exam because of his evil nature, but Ryuu explained that he couldn't make him a Kaiou simply because of his lack of skill.

The truth is that Retsu already possessed great skill in Chinese martial arts at that time, and it's likely that Kaiou Ryuu simply wanted to motivate him further. Following this incident, Retsu probably began training more intensely. For example, he was known for using his hands and feet to sculpt a perfectly round sphere from stone. One day, during training at a temple, Retsu killed his sparring partner. Perhaps this is why he was imprisoned, but it was never explicitly stated. Eventually, Retsu earned the title of Kaiou. In the anime, it's stated that Ryuu bestowed the title upon him not only because he considered his skills to be good enough, but also at the suggestion of Kaiou Dorian.