Akatsuchi

is an Iwagakure shinobi.

Background
In the anime, Akatsuchi was present during a council meeting to discuss an invitation from Konohagakure and Sunagakure to join an impromptu Chūnin Exams they would be hosting together. As Ōnoki arrogantly believed this was an attempt by the two villages to better gauge Iwagakure's strength for an upcoming fight, Akatsuchi simply suggested they just turn down the offer, to which Ōnoki firmly agreed.

Personality
Akatsuchi is a very jovial individual who always seems to have a cheerful disposition. He is also somewhat childish and laid-back, witnessed through his excited at the prospect of flying once again, even though there was the possibility that they were going off into a battle. He was even excited when he thought Deidara survived the battle against Sasuke Uchiha, despite Deidara being a criminal and their enemy. During battles, however, he is level-headed and efficient as the Tsuchikage's bodyguard. He is also fiercely loyal to the Tsuchikage, and refused to leave his side when he heard of Sasuke's fight, just in case Ōnoki's hip went out. Deidara also attested to the fact that Akatsuchi rarely ever leaves Ōnoki's side when he fought the two.

Appearance
Akatsuchi is a large and imposing man, with dark eyes and black hair that spikes out at the back from underneath his bandanna-styled forehead protector. He also has large cheeks, and a plump nose which give him an overall look of constant joviality. He wears the red Iwagakure uniform which has both its sleeves, underneath his flak jacket, and accentuates it with a yellow scarf which he wraps around his neck.

In later years after the Fourth Shinobi World War, Akatsuchi grows a beard and seemingly discards his forehead protector except his yellow scarf. He also ties his hair in a ponytail. He wears a brown kimono and pants.

Abilities
Akatsuchi has proven himself a capable shinobi. As his size belies, he is quite fast, capable of moving at high speeds as seen from him rushing to the Tsuchikage's side after reacting to the Fourth Raikage's actions which were interpreted as aggressive during the Kage Summit. He has also shown an amount of strength as well as stamina, being able to effortlessly carry the Tsuchikage, his luggage, and his own for an extended period of time.

Nature Transformation
Akatsuchi has also displayed proficiency in using Earth Release techniques. He can mould and expel a large rock golem from his mouth, which is capable of biting off a Zetsu clone's head, and pulling him from Akatsuchi's body. Such a golem can also be used to shield himself and allies from opponent's attacks.

Five Kage Summit
He was setting off with Kurotsuchi to escort the Third Tsuchikage to the Five Kage meeting, called for by the Fourth Raikage. When Ōnoki hurt his hips when trying to carry his bag by himself, Akatsuchi carried him along the way.

When the Raikage destroyed his table during the meeting, Akatsuchi and Kurotsuchi moved to protect the Tsuchikage after the Raikage's physical outburst, but was soon dismissed by Ōnoki. When White Zetsu appears during the summit, Akatsuchi and Kurotsuchi guard the Tsuchikage. Later, when Sasuke infiltrates the meeting room, Akatsuchi and the Tsuchikage decided not to engage him, moving out of the way to let the Fifth Mizukage, deal with him. Later, he is ensnared in Zetsu's Spore Technique. Seeing Sasuke escape Mei, Ōnoki suggests to two of them join the fight. Akatsuchi agrees, and uses the Earth Release: Golem Technique, creating a large, earthen golem which proceeds to bite and rip the Zetsu clone from Akatsuchi's body.

After Tobi told the story of the Ten-Tails and the Sage of the Six Paths, then declared the Fourth Shinobi World War, Akatsuchi returned to Iwagakure with the Tsuchikage and Kurotsuchi, where they were informed that the Earth Daimyō has approved of the Allied Shinobi Forces. He later assumes that the daimyō made a quick decision due to being informed of Madara and the loss of Tailed Beasts. When Ōnoki states that the war will result in a failure due to the ignorance of the youth, Akatsuchi recounts the strong words Gaara had directed towards him.

Paradise Life on a Boat
In the anime, Akatsuchi and Kurotsuchi were sent by the Tsuchikage in a diplomatic mission to improve Kirigakure's relationship with Iwagakure, along with Chōjūrō, who was also sent by the Fifth Mizukage on the same mission to stop Ganryū in the process.

Fourth Shinobi World War: Countdown
When news got to headquarters that Kisame Hoshigaki had managed to divulge the location where Naruto Uzumaki and Killer B were hiding, Ōnoki took Akatsuchi and Kurotsuchi with him to improve the defences. Once they reached the sea, Ōnoki noted that they would have to fly the rest of the way which pleased Akatsuchi greatly. On their way, they encountered Kabuto Yakushi and the reincarnated Deidara. Akatsuchi as well as Kurotsuchi expressed joy thinking that he had in fact survived his fight against Sasuke before being reminded by the Tsuchikage that the Deidara in front of them was no more than a reincarnation.

As the battle got under way and the Tsuchikage attempted to use a Dust Release technique, Akatsuchi stopped him, in fear for the Island Turtle's safety which the Tsuchikage had mistaken for part of the landscape. Using this opportunity Deidara sends an explosive clay bird flying their way and detonates it. Akatsuchi however uses his golem to defend against the attack — saving them. As Ōnoki and Deidara took the battle higher in the sky, they flew so fast that Akatsuchi had trouble keeping up.

Fourth Shinobi World War: Confrontation
While the rest of the Alliances' forces moved out, Akatsuchi remains behind by the Tsuchikage's side. After Ōnoki's departure to meet Gaara on the battlefield, Akatsuchi joined the Alliance on the battlefield where he fought alongside his comrades.

Fourth Shinobi World War: Climax
When Ōnoki later re-entered the battlefield, Akatsuchi responded to the Tsuchikage's rallying of the troops with a fearsome war cry.

Epilogue
Years after the Fourth Shinobi World War, Akatsuchi accompanied Kurotsuchi, the Fourth Tsuchikage, to the Kage Summit in Konohagakure.

Creation and Conception
Kishimoto noted that for Akatsuchi's design, he simply took Ōnoki, and made him larger. Expounding on this, he noted that the nose shape he had created for the Tsuchikage, fit Akatsuchi as well, but noted that he did not intend for Akatsuchi to look like the Tsuchikage's child.

Video Games
In Naruto Shippūden: Ultimate Ninja Storm Generations and Naruto Shippūden: Ultimate Ninja Storm 3, Akatsuchi is a support-only character.

Trivia

 * means "Red Earth".