Jirōbō

was the physically strongest member of the Sound Four and the weakest overall, according to the other members of the Sound Four.

Personality
He disliked it when Tayuya used foul language or when she called him "fatso". Despite this, he proceeded to call Choji Akimichi fat near-constantly during their battle. At first Jirobo appeared as the silent yet slightly irritated member of the group; until the Sasuke Retrieval arc in which he revealed an overly sarcastic and arrogant persona. Like several other Sound Four, however, he had his own perception of morality, criticizing Shikamaru for what he saw as giving up on Choji and selling his teammates out.

Konoha Invasion arc
Jirobo made his first appearance with the rest of the Sound Four, erecting a barrier to keep other interfering in Orochimaru's fight with the Third Hokage. He 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 found the Sound Four, Jirobo allowed the rest of his group to go ahead of him while he used Earth Release Barrier: Earth Prison Dome of Magnificent Nothingness and the Chakra Absorption Technique combined to trap Team Shikamaru and drain their chakra at the same time. Shikamaru later had a plan to escape the barrier by making a hole where there was least amount of chakra. His plan succeeded only for it to turn out that Jirobo was just getting ready.

After Jirobo insulted Shikamaru, Choji, angered by this, challenged Jirobo to a 1-on-1 fight, allowing the rest of Shikamaru's group to go ahead. By using his Three Colored Pills, Choji was able to overcome Jirobo's cursed seal and kill him.

Abilities
Jirobo's fighting style consisted mostly of basic physical strikes supplemented with the ability to use his chakra to hold the earth solid. His physical strength was unbelievable, which was demonstrated when he held up a mountain-sized Choji when in Level 2 cursed seal form. He tore boulder-sized chunks of dirt out of the ground to throw, created barriers by tearing up massive sheets of rock, and could drain chakra with his Chakra Absorption Technique. He was almost always enormously hungry, and he could get the same energy from absorbing opponents' chakra that one would get from food. When in cursed seal level 2 form, his skin became red, his Mohawk became a mane down his back, and he gained ten times his normal strength.

Trivia

 * Jirobo can be seen during the Konoha Sports festival and the omake of Naruto Shippuden episode 129.