Kidōmaru

was a member of the Sound Four.

Personality
Kidomaru generally saw a battle as a game, and often played around with the opponent too much because he prefered to have fun seeing the opponent struggle. His speech also reflected this; when battling Neji Hyuga, he refered to Neji as a "minor character" and analyzed his situation using typical gaming language ("level" and "difficulty").

Invasion of Konoha arc
Kidomaru made a short appearance in this arc using a barrier technique along with the rest of the Sound Four: Jirobo, Sakon and Ukon, and Tayuya both from the inside and outside so that the Third Hokage could not escape, nor could the ANBU get into the battlefield. When Orochimaru fled, he used Spiral Spider Web to stop pursuing ANBU.

Sasuke Retrieval arc
Kidomaru used his web techniques to wrap everyone on Team Shikamaru. Neji Hyuga, using his Gentle Fist was the only one able to cut through chakra and escaped from the web himself and thus found him a good match with Kidomaru. They then battled, leaving the rest of the Konoha group to go ahead. 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. He activated Cursed Seal Level 2 and made the arrow go right through Neji who later closed all of Kidomaru's chakra points by transferring chakra through the web to kill him eventually. As Kidomaru dies, he mentions that he hasn't been pushed that far since Kimimaro.

Abilities
Kidomaru was the spider-like member of the Sound Four; he possessed four extra arms for a total of eight limbs, and had the ability to make webs. He made his webs through a special type of liquid that was created by infusing spit with chakra. He could also create a thicker gold liquid that hardened into a chakra-blocking metal. This hardened material could be fabricated into body armor, kunai, or his especially deadly bow and arrow. When in his Level 2 cursed seal form, he became even more spider-like; his skin became darker, he gained horns on his forehead, shoulders and elbows, and grew long white hair. He opened the third eye on his forehead to improve his accuracy (which he normally kept covered with his Sound forehead protector). However, as Sakon and Tayuya commented, he went into that state way too easily. He also gained the ability to control the path of his arrows with chakra and thread. His abilities were not kekkei genkai, but clan-related.

Kidomaru 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. Close combat was his worst type of fighting.

Quotes

 * "This game has a higher difficulty level than I thought!"
 * "Lord Sasuke... has willingly joined the Sound."
 * "Heh, smart aleck to the end."
 * "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!"

Trivia

 * He was the only member of the Sound Four to be seen wearing a Sound Headband.
 * Kido means "deception," and "-maru" is a common ending for male Japanese names. Thus, Kidomaru's name could be translated as "deception boy" or, more loosely, "con man."