Benga

was the chief officer at Hōzuki Castle. When Mujō fell ill, Benga became the acting Master of the Castle.

Personality
Benga was a callous individual. He disliked intellectual pursuits, considering strength to be the only reliable form of maintaining order. Despite being Mujō's subordinate, he looked down on him, thinking him to be soft on the prisoners because of his belief in the possibility of rehabilitation. He had no compassion for the prisoners, adopted a no-nonsense attitude with them, and was outright rude and harsh with them. At the same time however, he had proven himself to be corrupt, having solicited bribes and manipulating inmates' imprisonment terms. Regularly, he was wiling to take payment for special favours from the prisoners he was tasked with rehabilitating. Even more, he was a shamelessly ambitious man, having no loyalty to anyone, regularly abusing his authority to torment the prisoners and looking for any means to enrich himself. Even if it meant bringing harm to his own allies, Benga was willing to use any means to accomplish his own goals.

He was also a very sloppy man, enjoying regular drinks and leaving his office in a messy state. At the same time, he was an observant man, noticing sudden changes in the prisoners' activities.

Abilities
Benga had skill in ninjutsu, being able to perform Fire Release. He could create an ignition by performing the necessary hand seals, as he did so to incinerate Kokuri's parole order. He could unleash a fairly powerful blast at his opponent, engulf his hand in fire to enhance his attacks, and manipulate a long stream of fire akin to a whip. As a head official of Hōzuki Castle, he could also perform the Fire Release: Heavenly Prison, able to activate the seals on a target and release them completely. While acting as the warden, he gained access to its summon: a two-headed, fire-breathing hound passed down from warden to warden, used to hunt down prisoners who attempt to escape.

Mujina Bandits Arc
Benga lectured new prisoners on the rules of Hōzuki Castle at their arrival, being rude to Boruto Uzumaki even as he demonstrated interest in knowing what the rules were, and beat him when he expressed concern for Haie, who activated Mujō's branding by trying to escape. Later, he welcomed Sarada, a journalism student researching the prison. He answered her questions, shared his opinions, and showed her around the different areas of the castle.

Later, after the prisoner Kokuri was attacked by a prisoner, while still in the medical wing, Mujō decided to move Kokuri to a more secure cell. Benga however, as the chief officer in the prison, had final say in the matter as Mujō's position as "lord" of the castle was more figure-head. He declined the idea, insisting that they can't give prisoners special treatment. In truth, Benga was bribed by Tsukiyo to ensure Kokuri was left with little protection as possible to ensure his demise. Later, Mujō discovered Benga's extensive history of accepting bribes in the prison. Using this leverage, Mujō had the authority to take full command of the prison, successfully moving Kokuri to Boruto and Mitsuki's cell.

While Benga fretted over his recent bad luck, he learned to his shock that one of the medical workers lost his key pass, meaning a prisoner could have taken it. Benga had his officers search the prison extensively. Eventually, they discovered Arai had taken it when Boruto was escorted to the medical wing. After Arai was detained, Benga confronted Mujō about his concerns involving the sudden closeness between Kokuri and Boruto. Mujō however instructed him to not delve into this as the prisoners could turn violent on him.

Later, Tsukiyo requested that Kokuri be sent to Hōzuki Castle #2, where there were many members of the Mujina Bandits who could easily kill the traitor. While Tsukiyo offered to give Benga money Kokuri stole, he reluctantly said he didn't have the authority to do so. Later, learning of Kamata's lies about his current life via mail and gaining money through illegal gambling to help her, Benga confiscated Benga's money and threatening to reveal the truth about Kamata's convict status to his sick sister if he didn't help. He also bribed Kamata to see his sister again if he helped. Later, to Benga's fury, Kamata claimed to have not learned anything. Furious, Benga brutalised the prisoner and had him sent to solitary confinement while extending the man's sentence.

Afterwards, he was summoned by Mujō. After the warden revealed Kusagakure's decision to release Kokuri on parole, Mujō also revealed to have learned of Benga's abuse of authority to extend various prisoner's sentence and brutalising of them. Deciding he had no place in a place of correction, Mujō immediately fired him. However, Mujō's heart condition acted up. Benga swiped Mujō's medicine smugly watched as Mujō collapsed and was rushed to the medical wing. With Mujō now too sick to work, Benga gained full authority of the prison. He accepted Tsukiyo's earlier offer, destroyed the parole order for Kokuri and set into motion Kokuri's official transfer to the prison's second site.

When the waterline suddenly had a malfunction, Benga grew suspicious. He confronted Doragu, learning of Boruto asking about the different ships that come to the prison and even more concerning was that Sarada was talking to Tsukiyo. He later confronted her, who revealed to him that she knew all about his shady actions on the prison. Seeing her as a threat to his newfound position, he attacked her with his Fire Release. While she easily dodged the attacks, one of his blasts hit a pipeline, which exploded and knocked Sarada into a pit. Satisfied at his work, Benga called off all searches for Sarada. He investigated her belongings and found her notes, which confirmed she had been working with Boruto, Mitsuki, and Kokuri, and detailed their escape plan. Benga derailed their plan by draining the old water tank. He discovered that the Boruto in his cell was a shadow clone, and the knowledge of a breakout agitated the prisoners. He attacked Haie to prevent him from requesting reinforcements from Kusagakure, and summoned a two-headed, fire-breathing hound to hunt down the fugitives. When he was defeated, Tsukiyo convinced him to remove his Heavenly Prison so he'd deal with the fugitives, but killed Benga before doing following his own plan.