Sakon and Ukon

and his older brother were twin brothers and the apparent leader(s) of the Sound Four. To help distinguish between the two, Sakon wore beads around his neck and Ukon had a somewhat deeper voice. Also, their bangs were on opposite sides (Ukon's being on the left, Sakon's on the right).

Personality
Sakon enjoyed bad-mouthing the opposition. Orochimaru noted Sakon to be the fastest and strongest member of the Sound Four, traits Sakon was very proud of. When in battle Sakon liked to prolong the fight by toying with the opponent and use unnecessarily powerful techniques. This tendency of Sakon's caused him to slow down the rest of the group whenever he got interested in an opponent. Ukon was able to counteract this flaw by being more impatient and hasty than his brother, forcing Sakon to quickly end his battles.

Appearance
Both Sakon and Ukon have dark bluish-gray hair with long bangs that covered one eye. Each of the twins wore turquoise lipstick, and brown eyeliner, which made their appearance more feminine. They wore brown tunics with long black wristbands (which are mistaken for being part of his sleeves), black skin-tight shorts, and purple ropes tied around their waists. Sakon wears a dark-red, beaded necklace around his neck and a giant scroll behind his back. Both of the twins have a cursed seal planted on their foreheads which are covered by their bangs. At most appearances, Ukon is usually shown with a smirk on his face, and his head slightly tilted down.

Abilities
As stated by Orochimaru and Kabuto Sakon is fastest and strongest of the sound four,bested only by Kimmimaro. Sakon tended to toy around with his opponent while Ukon tended to finish them off quickly. They are shown to know a variety of ninjutsu from barriers to sealing jutsu. In the fight with Kiba both Sakon and Ukon were shown to have good tiajutsu abilities also.

Kekkei Genkai
Most of the brothers powers came from their kekkei genkai Soma no ko. It allows the brothers to merge with the bodies of others. Most of the time Ukon lay dormat inside of Sakon but he can pop out extra limbs to help Sakon,should he need it. Using this there tiajutsu abilties are increased, they also gain fast healing powers. These ablities are even more increased with the power of the curse mark. In 2nd state,their hair grows longer,they obtain armor(diffrent sides for each brother),and long horns. In this state they are able to merge with the bodies of others through a jutsu called Demon Parasite. As explained by Ukon he is able to break down his molecules with chakra and merge with others,slowly killing the victim from the inside out. As seen in the fight with Kankuro,Ukon is not use to being the lead body as such his stamina is below average.

Invasion of Konoha Arc
Sakon and Ukon made their 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. They later escorted Orochimaru when he fled.

Sasuke Retrieval Arc
The Sound Four escorts Sasuke Uchiha when he decides to join sides with Orochimaru. After Team Shikamaru caught up with the Sound Four, Sakon and Ukon were separated from the rest of the group by Kiba Inuzuka and Akamaru. They almost killed the two, but before they could do so they were stopped by Kankurō. Kankurō, with his puppets Crow and Black Ant, killed Sakon and Ukon with Black Secret Technique Machine One Shot, saving Kiba and Akamaru.

Creation and Conception
Sakon was the final member of the Sound Four to be created by Masashi Kishimoto. After struggling to decide who Sakon should fight, Kishimoto decided to have Sakon take part in a two-on-two battle against Kiba and Akamaru. Thus he created Ukon and placed him within Sakon's body so that they could act as one person.

Trivia

 * Sakon can be seen in the omake of Naruto Shippūden episode 129 with Kidōmaru, picking masks.
 * In Naruto: Ultimate Ninja 3, while playing as Sakon, holding up on the D-Pad (healing move) Sakon's name temporarily changes to Ukon.
 * Sakon's hair is shown as dark blue in the manga. In the anime it has a light bluish-gray color.
 * Sakon and Ukon were the only ones of the Sound Four to be defeated in their normal forms.
 * According to the Naruto Official Databook:
 * Sakon's favorite phrase is: "The first and only".
 * Ukon's favorite phrase is: "The older brother up the younger brother".
 * Sakon and Ukon had completed 46 official missions in total: 20 D-rank, 15 C-rank, 8 B-rank, 2 A-rank, 1 S-rank.