Jirōbō

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

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

Konoha Invasion arc
Jirobo makes his first and short appearance here after Orochimaru takes the Third Hokage along with Sakon and Ukon, Tayuya, and Kidomaru. He is 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 find the Sound Four, Jirobo allows the rest of his group to go ahead of him while he uses 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 has a plan to escape the barrier by making a hole where there is least amount of chakra. His plan succeeds only for it to turn out that Jirobo was just getting ready.

After Jirobo insults Shikamaru, Choji shows his anger of this by challenging Jirobo to a 1-on-1 fight leaving the rest of Shikamaru's group to go ahead. Choji takes his first pill and as the fight goes on, he is eventually forced to take the last pill which forces death to occur. Jirobo, at some point in the fight, activates his cursed seal. Choji easily defeats him with one last punch and the force kills him.

Abilities
His fighting style consists mostly of basic physical strikes supplemented with the ability to use his chakra to hold the earth solid. His physical strength is unbelievable, which is demonstrated when he holds up a mountain-sized Choji Akimichi when in Level 2 cursed seal form. He tears boulder-sized chunks of dirt out of the ground to throw, creates barriers by tearing up massive sheets of rock, and can drain chakra with his Chakra Absorption Technique. When in Level 2 cursed seal form, his skin becomes red, his mohawk becomes a mane down his back, his eyes turn black, he gains numerous wart-like bumps on his forehead and shoulders, and he gains ten times his normal strength. It is mentioned various time in the anime that he is almost always enormously hungry, and he can get the same energy from absorbing opponents' chakra that one would get from food, as well as vice versa.

Trivia

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