|Suigetsu is a lean-built young man of average height, straight white hair with a light-blue tint to it, purple eyes and like all members of the Seven Ninja Swordsmen of the Mist pointed teeth — one of which sticks out even with his mouth closed. He wears a purple, sleeveless shirt with grey pants, sandals and a belt around his waist with water bottles attached to it. He also wears another belt strapped to his chest which he uses to carry the Kubikiribōchō. Due to his special body, Suigetsu is able to alter his body size at will, usually to aid in his techniques and when rendered unconscious, he is reduced to a jelly-like state. Whenever he is seen recovering from these unconscious states he is placed in a large tank of water and resembles a fish-like being.
Suigetsu appears to be indifferent, caring only for a few things around him. He spends a considerable amount of time mocking and/or being beaten up by Karin. Despite showing initial dislike towards his team-mates, Suigetsu has grown fond of them, and was willing to risk his own life to protect them against the Eight-Tails. Kisame Hoshigaki claims that Suigetsu is a prodigy in the art of murder, as he has a habit of chopping off his victim's limbs before beheading them Suigetsu, despite addressing him with the honourific term "senpai", wants to defeat him and take his sword, noting to Sasuke that he will one day serve him as "shark fin soup" (a reference to Kisame's shark-like appearance) after Sasuke suggested that he was not yet strong enough to defeat Kisame, showing it to be a sign of sarcasm rather than respect for Kisame. As a prodigy at the art of murder, Suigetsu has a certain love for killing, but he refrains from doing so at Sasuke's request. However, there are several occasions where he has killed people when he believed Sasuke wouldn't notice. Suigetsu has been shown to have thoughts such as "just this once" and "he'll forgive me". However, he was noticeably upset that Sasuke killed several samurai during the attack on the Kage Summit, pointing out how many times Sasuke had told him not to kill anyone. He was described to have a belligerent personality, witnessed through his hostile and aggressive attitude most times. Suigetsu has a passion for collecting exotic swords: he made it his goal to collect all the swords from the Seven Ninja Swordsmen of the Mist. He took Zabuza Momochi's Kubikiribōchō and joined Hebi only to take Kisame Hoshigaki's Samehada. He even went into great detail to explain about the seven swords to Jūgo, with a passionate tone to his storytelling. However, his passion doesn't seem to be entirely limited to the seven blades, as he also expressed interest in Darui's sword. His ultimate goal however, is to collect the seven blades, so he can reform the Seven Ninja Swordsmen of the Mist and become their leader. Along with this passion for collecting swords, Suigetsu is very mischievous and as such, takes great joy in foiling Karin's plans to be alone with Sasuke and has stated that it is his second favourite thing to do. By his own admission, Suigetsu has an impulse to cut things up, be it a people or relationships, as he does with Sasuke and Karin. Suigetsu apparently likes animals somewhat seen from his attempt to play with the talking ninja cats from the abandoned Uchiha warehouse at one point. He also lectured Sasuke on treating animals better after Sasuke used Manda to shield himself from Deidara's suicide technique, which resulted in Manda's death. Suigetsu also has what seems to be a chronic fear of Orochimaru, which is to be expected due to the latter imprisoning and experimenting on him. This fear was witnessed when Sasuke declared that he would revive Orochimaru and Suigetsu's ensuing attempt to dissuade him from doing so. When Orochimaru was revived, Suigetsu even refused to stay on the same side of the cave with him, retreating to opposite ends depending on where Orochimaru went.