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", and he always criticized her when she did. 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 and short appearance here after Orochimaru took the Third Hokage along with Sakon and Ukon, Tayuya, and Kidomaru. He was seen using a special barrier technique with the rest of the Sound Four to prevent the Third Hokage from escaping the battlefield and to not let anyone in. Anyone who touched the barrier instantly caught on fire.

Sasuke Retrieval arc
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 showed his anger of this by challenging Jirobo to a 1-on-1 fight leaving the rest of Shikamaru's group to go ahead. Choji took his first pill and as the fight went on, he was eventually forced to take the last pill which forced death to occur. Jirobo, at some point in the fight, activated his cursed seal. Choji easily defeated him with one last punch and the force killed him.

Abilities
His 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 Akimichi 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. When in Level 2 cursed seal form, his skin became red, his mohawk became a mane down his back, his eyes turned black, he gained numerous wart-like bumps on his forehead and shoulders, and he gained ten times his normal strength. It was mentioned various time in the anime that he was almost always enormously hungry, and he could get the same energy from absorbing opponents' chakra that one would get from food, as well as vice versa.

Trivia

 * He was the only member of the Sound Four who was seen using an elemental type jutsu.