Kidōmaru

was a member of the Sound Four and, as said by Orochimaru, to be the smartest.

Personality
Kidōmaru generally saw a battle as a game, and often played around with the opponent too much because he preferred to have fun seeing the opponent struggle. His speech also reflected this; when battling Neji Hyūga, he referred to Neji as a "minor character" and analyzed his situation using typical gaming language ("level" and "difficulty"). He is also extremely arrogant with his opponents, and sometimes swears if he is in a tough situation.

Invasion of Konoha arc
Kidōmaru made his first appearance with the rest of the Sound Four, erecting a barrier to keep others from interfering in Orochimaru's fight with the Third Hokage. He later escorted Orochimaru when he fled.

Sasuke Retrieval arc
The Sound Four escorted Sasuke Uchiha when he decided to join sides with Orochimaru. After Team Shikamaru caught up with the Sound Four, Kidōmaru allowed the rest of his group to go ahead of him while he caught and toyed with their pursuers. Neji is able to free everyone from Kidōmaru's webbing using his Gentle Fist and engaged Kidōmaru in battle. He fought Neji using his spider techniques which, even with Neji's Eight Trigrams Sixty-Four Palms, were difficult to defeat. He revealed a golden armor that was made from liquid secreted from his sweat glands that protected him from powerful attacks to prevent Neji from closing his chakra points. He used the same element of spider silk to make an arrow and discovered the Byakugan's blind spot. Although he was able to hit Neji, Neji used the arrow to close all of Kidōmaru's chakra points by transferring chakra through the web, eventually killing him. Prior to his demise, Kidōmaru claimed that Sasuke has chosen the path of revenge, and it was useless for the retrieval team to try, and that Neji was the second person to force him to fight at full strength, the first being Kimimaro.

Abilities
Like the rest of the Sound Four, Kidōmaru was skilled with creating barriers and seals. When in his Level 2 cursed seal form, his skin became darker, he gained horns on his forehead, shoulders and elbows, and grew long white hair. Kidōmaru was an excellent tactical analyzer, capable of figuring out his enemy's weak point quickly and efficiently, and also enjoyed playing with his enemies before he killed them. He seemed to prefer fighting from a distance, lending him a considerable advantage and allowing him to avoid close-combat, his worst type of fighting.

Sticky Gold
Kidōmaru possessed four extra arms for a total of eight limbs, a third eye to improve his aim, and had the ability to make webs through a special type of liquid that was created by infusing spit or sweat with chakra. He could make this into webs of chakra, that only Neji and his gentle fist were able to cut, or create a thicker gold liquid that hardened into a chakra-blocking metal. This hardened material could be fabricated into body armor that could completely defend him from physical attacks and impacts, kunais and other throwing weapons, or his especially deadly bow and arrows that refined its attack potential with every use. In keeping with his spider-theme, he could summon the Kyodaigumo, a giant spider that could use the Rain of Spiders technique.

Trivia

 * He was the only member of the Sound Four to be seen wearing a Sound Headband.
 * means "demon child," and is a common ending for male Japanese names.
 * Kidōmaru can be seen during the omake of Naruto Shippuden 129. He is picking masks with Sakon nearby.

Quotes

 * "This game has a higher difficulty level than I thought!"
 * "I guess it was more fun this way... but now game over!!"
 * "What kind of a freak is this guy?"
 * "The weakest one in the game always goes down first!"