Jigen

was a novice monk that became the vessel of Isshiki Ōtsutsuki and eventually had his body completely taken over by Isshiki invading it, acting as an Inner of Kara and its surrogate leader.

Background
Around the time that Kaguya Ōtsutsuki and Isshiki Ōtsutsuki arrived on Earth, Jigen was a novice monk and after Kaguya left him for dead, Isshiki assaulted Jigen, during which he shrunk himself and entered the monk's ear in order to survive. Through having his nutrients absorbed from within his body, Isshiki began gaining control over Jigen's body, and eventually Jigen lost full control of it. Afterwards, Isshiki embedded his Kāma in Jigen, but because Jigen's body wasn't powerful enough to sustain his chakra, Isshiki opted not to revive himself in Jigen, instead waiting until a more suitable vessel could be found.

In time, Isshiki used Jigen's body to form a clandestine organisation to help achieve his goal, dubbed Kara. Eventually, Jigen found and purchased Kawaki from his abusive father for a large sum of money, to use as a potential new vessel. After taking custody of the boy, Jigen introduced himself as his new father and reassured him. He would later attempt to transfer Kāma to Kawaki and fourteen other boys in an experiment conducted with the help of the Kara scientist Amado Sanzu, with Kawaki being the only known success and thirteen dying outright. Despite promising him safety, Jigen put Kawaki through gruelling training to master the Kāma and would constantly berate him as only having value as a vessel, striking the boy whenever he questioned him. As with the rest of Kara, Jigen also had his body extensively modified by Amado's Scientific Ninja Tools. Isshiki plotted to feed Jigen, along with himself still living within the monk's body, to the Ten-Tails, in order to fulfill the requirements to have it bloom into a God Tree, despite the resultant Chakra Fruit will be of lower quality due to the sacrifice's poor health and strength.

In the anime, another Inner Ōga was enhanced to help Amado with his research on the human heart. When she attempted to study Jigen's, Isshiki considered it treason, and destroyed a portion of her brain before she escaped.

Appearance
Despite his ancient origins, Jigen's appearance managed to retain a youthful physique due to Isshiki Ōtsutsuki's influence. He was a fairly tall man of light complexion. He sported a shaved head, apart from a long mohawk of black hair tied in a long ponytail style reaching his lower-back, pronounced eye ridges void of brows, a broad nose, and large black eyes. Some time after Isshiki took control of him, he gained a diamond-shaped Kāma mark on his chin and a Roman numeral "Ⅳ" tattooed below his left eye. The area where his stomach was seemed to be completely black. He also wore black nail polish on his fingernails and toenails, five red earrings on the top of each ear, and an additional one at the bottom of each ear.

In his first appearance, he wore the black hooded cloak with maroon lining typical of Kara members, along with dark capri pants and sandals, and a dark collar. In later appearances, he donned a flowing white robe with black vertical lines on the sleeves and coattails and his personal crest on the back, loosely fastened at the waist with a tasselled belt, worn with matching red hair tie, collar, waistband, bracers, and pants, all decorated with red pearl studs and simple sandals.

Abilities
As the leader of Kara, Jigen's body was modified with Scientific Ninja Tools, and was a complete monster in terms of power and ability. The strongest of his organisation, his might far surpassed even the other Inners. As the current vessel of Isshiki Ōtsutsuki, all his power comes from the exceedingly powerful Celestial Being who resided within his body. From just sensing his power, Ino Yamanaka opted that the Seventh Hokage confronted him with aid. Even without accessing his full power, he could still fight and pressure both Naruto and Sasuke Uchiha, the two strongest shinobi in history simultaneously. However, only from when Isshiki decided to draw out his full power into Jigen's body was he able to defeat Naruto and Sasuke at all as prior, the two shinobi took Jigen to his limits, whereupon accessing full power was Jigen able to decisively defeat both of them, sealing the former while nearly killing the latter. The fight severely weakened Jigen to the point he was forced to withdraw his attempt to retrieve Kawaki and engage in a two-day recuperation process (ten in the anime).

Ninjutsu
As Isshiki's vessel, his body was able to channel the various abilities of the Celestial Being. He could produce black rods capable of draining chakra from the victim and could also shrink matter to microscopic levels and just as easily return it to normal so rapidly. He could also manifest various stored objects from a pocket dimension, which he could perform with the most minute of gestures such as a mere wave of his hand or even just a flick of his fingers. He utilised these abilities to launch the black rods at microscopic size into the bodies of his foes while leaving them completely unaware, before returning them to their original size to instantly inflict catastrophic injuries. He could also enlarge them whenever necessary to counter armed blows from enemies. He could also apply the ability to his own body, allowing him to disappear from sight and manoeuvre around the battlefield, as if teleporting, fast enough to catch the likes of Naruto and Sasuke off-guard. The limitations of this ability remain unknown, but Sasuke was able to track his movement even at a microscopic level thanks to the Sharingan. Once activating Kāma's full power, Jigen became able to use these abilities at an even greater level, able to spontaneously summon large black rods instantly to incapacitate Naruto and Sasuke and even form them from his neck to block Sasuke's sword attack.

Physical and Chakra Prowess
Through Isshiki's control, Jigen was an extremely skilled melee-combatant with both weapons and hand-to-hand combat. He had shown tremendous speed and strength, easily kicking Naruto away, impressing the Hokage with his reaction, and effortlessly catching a punch from Kawaki when he had Kāma activated, causing Kawaki visible pain by merely squeezing his arm. He was also highly durable, suffering no injuries from a kick to the jaw from Naruto in his Six Paths Sage Mode. While he had Kāma activated, Jigen was easily capable of handling Naruto in his Six Paths Sage Mode in physical combat and would have dealt a lethal blow had Sasuke not interfered both times. Upon accessing Kāma's enhanced state, Jigen effortlessly defeated Naruto and overpowered his shadow clones within a matter of moments. He had also displayed remarkable proficiency with a large black rod to easily parry blows from Sasuke, despite his skill in kenjutsu. Even while severely weakened from his battle with Naruto and Sasuke, he remained fully capable of matching Koji Kashin in hand-to-hand combat.

As Isshiki's vessel, Jigen wielded tremendously powerful chakra, compared to Naruto in his Six Paths Sage Mode form by Kawaki. When he activated Kāma's transformed state, his chakra was such that it intimidated Sasuke into fleeing and later on unnerved both him and Naruto. Even without Kāma, his sinister chakra was already strong enough to terrify Ino Yamanaka to the point of near-collapse, whereas she only felt a slight reaction upon sensing Delta's chakra. His reserves were shown to be able to maintain prolonged usage of his Kāma without issue against the likes of Naruto and Sasuke simultaneously, although using its full power for such a long period could still weaken him considerably, draining him of almost all of his chakra and taking two days to return to full power. Despite this weakened state, he retained enough chakra to battle Koji, using several of his techniques, with seemingly little drain.

Kāma
Jigen possessed a Kāma mark on his chin, which had caused various augmentations to him including tremendously enhanced longevity, having remained in his physical prime for over 1,000 years. It could be activated at will, causing it to spread across his entire body in nearly symmetrical sunburst patterns. He was able to pass a Kāma on to other individuals through the aid of science, albeit with a low success rate, more often resulting in death, and with Kawaki's coming from him, he could synchronise with the latter's Kāma to open a portal to his current location.

With his Kāma activated, the mark spread across his chin, eyes, and body in vertical sunburst patterns. In this state, Jigen's power was already amplified to such levels that he was able to pressure both Naruto and Sasuke at once for an extended period of time. His physical parameters were greatly enhanced, his strength being such that his blow pushed Naruto back noticeably despite him having properly blocked it, shocking the Hokage by the feat, resilient enough to be completely uninjured and instantly recover from being harshly kicked to the jaw by Sasuke. His prowess with absorption could absorb large quantities of chakra from tailed beast-like entities, and effortlessly neutralise Naruto's powerful Rasengan techniques and Sasuke's Amaterasu, being unaffected even while in his microscopic state. However, he could not manoeuvre as efficiently while absorbing. In the anime, he was shown charging up a beam of energy, similar to Kawaki.

When accessing the full power of the Kāma, his enhanced state progressed it far enough to make a horn protrude from his left temple and wrap around the back of his skull, resembling a crown. In this state, Jigen gained an even more tremendous boost in power, able to easily defeat both Naruto and Sasuke. He was so fast and strong, he could easily dodge Sasuke's Complete Body Susanoo's sword slash and then penetrate it with a single kick to send Sasuke flying as well as punch Naruto out of his Tailed Beast Mode and causing him to draw blood with a single attack. Along with that, he was able to make Naruto and Sasuke bleed severely with just a few punches, even reverting Naruto back to his base form.

Kara Actuation Arc
In the anime, Jigen called a meeting with the Inners, informing them of the destruction of one of their facilities in Amegakure set by an Outer.

After a failed plot to grow another God Tree, Jigen held a private meeting with Victor, who claimed Deepa to be responsible. While voicing suspicion of his claim, Jigen let Victor off with a warning.

Ao Arc
In the anime, Jigen contacted Amado to discuss the development of Kawaki, knowing that he was already into Phase 3 of their plans. Amado insisted that while it was technically true, the data was still too weak to continue with Phase 3. Jigen decided to transfer Kawaki for a field test. Victor then appeared, offering his new stealth blimp for the transfer. Later, despite the smooth moving of Kawaki onto the blimp, there was a malfunction, causing the blimp to crash, which Jigen was alerted to.

Jigen held a meeting with the other members of Kara to discuss the urgent situation, during which Koji was given the task of recovering Kawaki. As he dispelled the genjutsu, Jigen voiced that their group must recover the vessel at all costs. In the anime, not trusting Victor's story about the mishap in the Land of Valleys being caused by Deepa, Jigen had Deepa's corpse recovered and Amado restore his brain to learn the truth of Victor's betrayal. No longer needing Deepa's remains as a liability, Jigen had Amado dispose of Deepa and had Koji Kashin go kill Victor. During a physical checkup on his body from Amado, Jigen revealed his suspicions that the blimp's crash wasn't Victor's doing, but rather a third party took advantage of Victor's betrayal to mask their own actions. Amado said he would investigate it.

Kawaki Arc
While eating a meal with Delta, she voiced her frustrations about the time it was taking to recover Kawaki, during which Jigen gave her permission to partake in the recovery of the vessel with the condition that she follow Koji's ways. Later, after Delta's decisive defeat by the Seventh Hokage, upon Jigen silencing the argument between her and the other Inners and asking what Koji was doing, she reported that Koji was holding off on retrieving Kawaki to study Boruto Uzumaki after learning that the boy obtained his own Kāma. Smirking at this development, Jigen deduced that Momoshiki Ōtsutsuki was behind this. Later, Jigen went to an undisclosed location accessible only through space–time ninjutsu to see an immobilised beast. He spoke nonchalantly to it, hovering above and addressing it as Ten-Tails. The "Ten-Tails" tried to eat Jigen but failed to do so as Jigen was out of reach. Jigen stated that it was too soon as he needed to complete the vessel. Jigen then used his Kāma to absorb more of its chakra and his physical form changed into an Ōtsutsuki who supposedly partnered with Kaguya Ōtsutsuki briefly. After absorbing the beast's chakra, Jigen intended to visit Boruto and Kawaki.

Using the connection between his and Kawaki's Kāma, Jigen teleported to Naruto Uzumaki's house instantly to bring back Kawaki. He noticed Koji's toad and watched suspiciously as it was incinerated by Koji before apologising to Naruto for his rude arrival and stating he desired no confrontation, only to take Kawaki and leave. When Naruto rebuked his politeness with hostility and attacked him, Jigen easily subdued Naruto by pinning him down with rods before turning to Kawaki, telling his wayward adopted son his rebellious stages and momentary "vacation" is over, only for Kawaki to attack him. Easily restraining Kawaki, Jigen, exasperated by the preference of his prosthetic over his hand that held Kāma, stated that the arm was just a monitoring device no different than the seal he gave him. When Kawaki defended Naruto, Jigen berated him for not believing he was just used as a bait and tightened his grip around Kawaki's hand, twisting it painfully, and stated that he was the only one who did anything for Kawaki's sake and that Naruto was just a peace-obsessed idiot, stating he would chop off Kawaki's prosthetic hand and leave it behind so he could fix his hand when they returned to the base. Kawaki's Kāma activated and a horn grew out of it, surprising Jigen with how much Kawaki's mark advanced. Naruto then kicked him away and Jigen, seeing his foe won't back down, activated his Kāma to begin fighting the Seventh Hokage, intent on killing him for his interference. When Kawaki offered himself up in exchange for Naruto not being hurt, Jigen was willing to agree as long as he was cooperative but seeing Naruto's determination quickly changed his mind, seeing no compromise.

He then teleported Naruto to another dimension and attempted to strand him there but Sasuke arrived and kicked Jigen away. Jigen calmly identified Sasuke's identity based on his Rinnegan and criticised him for having a lousy timing that made them now pitted up against him, unfazed at facing the two without restraints. Swiftly displaying his overwhelming might, Jigen faced the two legendary shinobi, using his seemingly instant vanishing and black rod manifestation ability to easily dodge their attacks and impale them while shrugging off any attacks that did connect with Kāma's powers, until the repeated performance ultimately let Sasuke deduce the true nature of Jigen's ability. Jigen simply praised Sasuke for his analysis before deeming him the one he should eliminate first. As the two Konoha-nin began anticipating his patterns and pressured him into a retreat, Jigen praised his foes' performance and thanked them for revealing his weaknesses to him before warning them in return that they would never have that same luck again as he revealed his Kāma's full power.

While Naruto was unimpressed by Jigen's new look, Sasuke revealed his findings, knowing about the existence of Isshiki and his juvenile Ten-Tails, knowing about the new Ōtsutsuki's goal to drain the entire planet of all its chakra, angering Jigen as he realised Sasuke had accessed the location he sealed his Ten-Tails in. This prompted the two shinobi to fight with their full power. Despite their strong avatar forms and teamwork, Jigen easily ploughed through their defences and proceeded to swiftly wear down and pummel his foes into his submission. However, as he had them beaten, the black centre of his abdomen began to visibly crack, causing Isshiki to scoff at the limits of Jigen as a vessel and voiced his desire for Kawaki. Deciding to finish things quickly, he restrained the two foes by impaling them with his black rods and decided to keep the Jinchūriki alive while killing Sasuke due to his Rinnegan's Space-Time Ninjutsu. Accepting the truth, Naruto had his clones hold off Jigen while he convinced Sasuke to escape. Jigen revealed that he was after Boruto Uzumaki for his Kāma before sealing Naruto in a giant kettle-like jar. However, soon afterwards, Jigen finally collapsed over the strain, even shedding a tear, as the black centre of his abdomen cracked even more. Isshiki cursed his unworthiness to be his vessel as Jigen teleported away.

Back at Kara's headquarters, apparently back in control, Jigen was hooked up by Amado to treat his body. The man voiced his disapproval of Jigen being so reckless with his body, noting that it would take at least two days to fully recover. Jigen voiced that he couldn't help but get excited after seeing how far and quickly Kawaki's Kāma was evolving and him synchronising with it. He theorised that it was because of his exposure to Boruto's own Kāma, also believing that Boruto was going through a similar development. From this, Jigen strongly believed the two of them would become "perfect" Ōtsutsuki and form a God Tree to consume the planet. He also assured Amado that everyone would get what was promised. Later, when Jigen had not even returned to 10% power, Koji arrived, intent on killing him. Jigen was talking with Code, who was guarding the Ten-Tails and told him to stay put while revealing Boro had not contacted him again, when Koji arrived in his quarters. Jigen at first cordially welcomed him and asked him on his mission but when Koji questioned on how he was able to so easily appear before Kawaki, Jigen coldly dismissed the question and revealed that he was aware that Koji and Amado had betrayed him and that they had crashed the airship to let Kawaki escape. He questioned their motives as all the Inners had collectively agreed on obtaining the Chakra Fruit but was ignored by Koji who attacked him with shuriken. Effortlessly avoiding the attack, Jigen blindsided and impaled Koji with multiple black rods, intent on having him tell everything before killing him, but found it was a Shadow Clone.

Commenting on his cheekiness, Jigen looked on as Koji declared he had no interest in the Chakra Fruit and just wanted to kill Jigen. As Jigen continued to repel Koji's various assaults, he voiced that the latter was nothing but a tool, having committed himself so fully to one goal. As Koji continued his attack while Jigen fully unleashed his Kāma, he eventually caught Jigen off-guard, summoning a giant wall of flames. As Jigen failed to absorb them, Koji explained that he summoned naturally occurring flames void of chakra, meaning the mark was powerless before it as the flames began to consume him. Jigen attempted to shrink the flames, but his still depleted chakra made it impossible, so his body was incinerated, killing both Jigen and Isshiki. As Kawaki's Kāma hadn't yet extracted all of Isshiki's data, Isshiki was forced to be resurrected in Jigen's body, the power boost allowing him to completely shrink the flames into extinguishment.

When Isshiki fought against Naruto in search for Kawaki, Naruto's Baryon Mode drained him of his already short lifespan, and upon Kawaki using a shadow clone as a decoy, Jigen's body finally reached its limit, collapsing to dust, resulting in Isshiki's death.

Trivia

 * The word was used in an advertising for climactic battle against Jigen in an issue of Weekly Shonen Jump, with the furigana pronunciation given as Jigen's katakana name, potentially suggesting that it is its intended meaning. Other possible meanings include, , and.
 * As the vessel for Isshiki, Jigen's powers draw inspiration from Issun Kotaro, a fairy tale hero from Japanese folklore who was only an inch tall. As a boy he went on an adventure to rescue a girl from an ogre, triumphing after being swallowed by it and using his sword — a needle — to attack it from within. He then claimed the ogre's magic hammer, Uchide no kozuchi, and used it to transform into a full-sized adult.