Shimotsuki Ryuma was a legendary samurai from Wano Country who was turned into a General Zombie by Gecko Moria hundreds of years after his death. He is the same Ryuma from Oda's previous one-shot manga, Monsters. His corpse previously possessed Brook's shadow to animate him while on Thriller Bark. When he was alive, he possessed black hair which was tied in the end with a topknot. He also wore a simple khaki samurai gi and simple zōri sandals. As a zombie, Ryuma is noticeably shorter than Brook. He has several bandages covering part of his skull face, which has no eyes and no nose, and wears a samurai gi with intricate designs more detailed than his original garb. He also wears geta instead of the zōri sandals of his past life, as well as a blue stomach band with a swirling design. Ryuma's mouth is partially covered by the blue scarf he wears, his black hair has turned white, and he keeps Shusui strapped to his right hip. In life, Ryuma followed a strict personal philosophy centered around justice and honor. Ryuma strongly believed that saving a life was a debt that must be repaid by those with virtue, and that repaying this debt was the way of a true swordsman. To this end, Ryuma would occasionally follow the request of someone he owed almost blindly, even when it contradicted his other beliefs. He also believed that a battle should be measured by what was protected instead of how much fame was gained.
As a swordsman, Ryuma had a peculiar habit: whenever someone touched their sword sheath with his, even by accident, Ryuma would immediately take this action as a form of challenge for a duel to the death. This behavior stems from Ryuma's belief that the sword is the swordsman. Despite his honorable intentions, this habit would get him into needless and bloody confrontations. Ryuma, having heard the reputation of "King", hoped to one day fight against him. He believed that this King must hold a great "Warrior's Soul" and would make a worthy adversary. The irony however, is that he himself was "King"; because the name, "King", was given to him by the people he saved, he unfortunately did not know it himself. Ryuma also had poor money management skills. Because of this, Ryuma would often unfortunately find himself penniless and hungry for days. As a zombie, Ryuma has mannerisms similar to those of Brook, such as his perverted nature and his distinct "Yohohohoho" laugh. These similarities exist because he has Brook's shadow animating his corpse. Though Ryuma has Brook's core personality, he possesses a slightly different outlook on things. He has abandoned his past as a part of Brook, and every memory connected with it; because of this, while Brook cherishes his afro, Ryuma sees it only as an eyesore. Ryuma also sees it as a weakness of Brook's to be exploited in their duel. He also has a decidedly sadistic streak, behaving quite cruelly towards his "former master" Brook; when fighting him, Ryuma seems to enjoy inflicting both physical and psychological pain as well as toying with him when he could have won quickly and easily, being the far more powerful of the two. He seems to retain a fondness for battle that is more in line with his body's samurai origins. He felt deep shame about himself after being defeated by Zoro. Ryuma possessed immense physical strength, as the force he applied in his swordsmanship allowed him to decapitate an enormous dragon with a single slash He also cut a copper statue in half. Ryuma was also an extremely fast runner with high endurance, as he could sprint great distances, and could jump to and land safely from great heights. His physical prowess supplemented with his sword skills allowed him to sustain no injuries during his battle in Monsters.
Ryuma was legendary in the Wano Country for his immense mastery in swordsmanship. He is a powerful Strong Blade type swordsman. His skills resembled a mix of Kenjutsu and Battojutsu. He could slice through copper, kill Cyrano, a first-rate swordsman, and an enormous dragon with little effort. He was renowned as the strongest swordsman of his time. Due to this, as well as his strong belief in protecting others, Ryuma was also called "King," the swordsman who carries the world's greatest "Warrior's Soul". At some point in time after his death, he came to be known as the Sword God in Wano Country and his skills continue to be regarded as legendary. Ryuma in his life possessed "Ryuo", another term for Busoshoku Haki in Wano. Although his skills haven't been revealed, after several battles wielding Shusui, he was able to turn it into a permanent Black Blade. As a zombie that possesses Brook's shadow, Ryuma can perform all of Brook's sword techniques. However, because Ryuma has a much stronger body than Brook does, the power of the techniques is amplified to a much higher level. The difference between the two is large enough that Ryuma could defeat Brook with only a fraction of his full strength. In addition to Brook's sword skills, Ryuma possessed immense strength that allowed him to knock out Nami, Usopp and Chopper in one attack, using the blunt edge of his blade; if he had used the sharp edge, he would have killed them. Because of this immense power, he can pierce through walls at a distance with the air pressure from his stab, completely cut through the spire roof of a tower with a single slash, and destroy an enemy's sword after just a few clashes, all things that Brook cannot do. As Brook noted, a battle between two users of the Power of Destruction such as Zoro and Ryuma will always end quickly. At some point in time of his life, Ryuma came to possess a sword called Shusui, one of the 21 Great Swords. It is distinguished by its black blade and flower-shaped guard. The sword remained with him even after he died. After Zoro defeated him, Ryuma gave the sword to him in hopes of satisfying the sword. Due to its association with Ryuma, Shusui is considered the national treasure of Wano Country. Before obtaining Shusui, Ryuma wielded a sword with a guard similar to that of Yubashiri that he used during his famous fight against the dragon.
