Tengen/Synopsis

History
During the Nara Period, Master Tengen spread Japanese Buddhism and preached what would become the foundation for jujutsu sorcerers.

Gojo's Past Arc
In the modern age, Master Tengen does not interact with the outside world. They use a barrier technique to protect both jujutsu schools and strengthen all auxiliary managers' barrier techniques. Their immortality-cursed technique must be reset once their body reaches a certain age. The technique will attempt to change bodies, forcibly evolving Tengen to a higher state, losing their will and potentially making them an enemy to humanity.

To prevent this, every five hundred years, Master Tengen must merge with a compatible star plasma vessel to rewrite their body's information. Once the body is refreshed, the cursed technique will also be reset. In 2006, the Star Plasma Vessel was Riko Amanai.

Two groups targeted the girl; the curse user group Q, who aimed to overturn the jujutsu world by having Tengen lose all reason, and the Time Vessel Association, the star religious group that worshipped Tengen as their deity. To ensure Riko's safety, Master Tengen had Masamichi Yaga assign his students Satoru Gojo and Suguru Geto to escort the girl to Jujutsu High before the merger on the full moon.

Riko is ultimately assassinated by Toji Fushiguro, who was contracted by the Time Vessel Association to kill the girl and prevent the impure merger. Even so, Master Tengen was somehow able to stabilize according to Yuki Tsukumo.

Perfect Preparation Arc
When Yuki and Yuji, Megumi, Maki, Yuta, and Choso enter the shrine and find nothing, Yuta tells them to leave because Tsumiki doesn't have time. However, just then, Master Tengen appears and greets them. Yuki confronts Tengen, asking why he did not say hello to her, to which Tengen replies that it wasn't the first time they've met. Tengen admits that he closed the Tomb of the Star corridor to them because they feared they were aligned with Kenjaku. Tengen reveals that Kenjaku was the sorcerer who was once Noritoshi Kamo but now has inhabited Suguru Geto's body. Yuji interrupts to ask why Tengen looks the way they do and is told by Tengen with amusement that while Tengen is immortal, he continues to age, and therefore Yuji would look the same after 500 years. Tengen explains to the group that 11 years prior, they failed to merge with a Star Plasma Vessel and were unable to prevent their cursed technique from evolving due to his advanced age. Tengen's individual awareness has degraded while they have, to an extent, become a part of the whole world.

Megumi and Yuta interrupt the conversation asking about Kenjaku's objectives and how to open the Prison Realm. Tengen explains that while they would like to agree to help unconditionally, they must require that Yuki Tsukumo, Yuta Okkotsu, and or Choso remain as his two guards. Yuta wonders why they need two guards if Tengen is immortal, while Maki asks if it's because of the seal. Yuki objects to this, saying they haven't told them why and how long they need to do it. Tengen explains Kenjaku's objective: to force the evolution of humankind throughout Japan. When Megumi wonders why Kenjaku didn't do this with idle transfiguration in Tokyo, Tengen explains that Kenjaku lacks the cursed energy to do so and that Kenjaku's chosen method is to forcibly merge the human population with Tengen, whose newly evolved state into becoming a part of all things can allow him to merge with beings other than Star Plasma Vessels.

Tengen explains that they are using advanced barrier techniques to willingly confine themselves, allowing them to maintain this current physical form. But if Kenjaku succeeds in their plan, all of humanity would attain a state like Tengen's, lacking boundaries between one another. This means that the evil of even one person would instantly spread to all others; if even one person goes out of control, impurities will flood the entire world, destroying it like Tokyo was. Yuji asks Tengen why Kenjaku would do this, but they are unsure because they cannot read human hearts.

Maki points out that Tengen could refuse to merge with anyone. Tengen explains the crux of their vulnerability: Now that they've evolved, they are more cursed spirit than human, which makes them a potential target for cursed spirit manipulation. They add that considering Kenjaku's abilities as a sorcerer, he may be able to seize them the instant of contact. This is why Tengen has kept himself hidden behind barriers and rejects everyone at the Tomb of the Star Corridor entrance. This is also why he requires guards; Kenjaku is the second most powerful barrier user behind themselves, and they are unsure when he'll undo the seals on the tomb. Yuki questions the timing of this plot: why now of all times, considering that he prevented Tengen's merging with a Star Plasma Vessel 11 years prior, forced their evolution, and wants to consume and control them through cursed spirit manipulation. She adds that Kenjaku was probably involved with Sukuna and has been a sorcerer for at least 1,000 years. Tengen implies that themselves, the Star Plasma Vessel, and the Six Eyes are all connected by fate.

Tengen reveals that Kenjaku lost twice to a sorcerer with the Six Eyes, and the second time he took no chances and killed both the Star Plasma Vessel and the Six Eyes less than a month after they were born. Nevertheless, the Six Eyes and the Star Plasma Vessel appeared on the day of the merging. Kenjaku switched to sealing instead of eradicating the Six Eyes and thus began searching for the Prison Realm because two bearers of the Six Eyes cannot appear simultaneously. However, the unexpected happened 11 years ago when Toji Zenin intervened. Tengen tells them that he was physically gifted through a Heavenly Restriction and was an anomaly completely untouched by cursed energy and destroyed their destiny. Then came a boy with curse manipulation, the final piece Kenjaku other than for the Prison Realm, which fell into his grasp six years ago.

When Megumi asks why the culling game is happening at all, Tengen explains the culling game uses the participants and the boundaries of the barriers in a ritual that conveys the human beings of this country to the other side. With that, Kenjaku will begin the merging with Tengen. However, to perform the ritual, he has undertaken certain binding vows. One of the vows stipulates that he isn't the game master. Because of this, even if Kenjaku is killed, the culling game will continue until all participants die or the players refuse to participate and die. Yuji notices that Megumi is upset by this but is unsure why. Yuta concludes that they have no choice but to participate and add a rule that allows Tsumiki and other unwilling participants to leave the game without repercussions. Megumi adds that they also should free Gojo because he could settle everything on his own. Tengen asks that they choose their guards first, as he has explained his rationale and is unwilling to compromise his security due to the danger it would bring.

Yuki and Choso step up for the guard position. Choso tells Yuji he will absolutely need either Okkotsu or Yuki's cooperation, especially if Kenjaku comes for Tengen. Tengen thanks the group before pulling out a box that is the "back" of the Prison Realm. Tengen explains that before Kenjaku found the Prison Realm, it was outside their barrier, and they believed it was overseas. By sealing the back gate, they attempted to conceal the location of the "front" without success. Tengen confirms for Yuji that this object would work as a back door, but the authority to open it still lies with Kenjaku, the bearer of the "front." To break it, they would need either the Inverted Spear of Heaven that nullifies cursed techniques and or the Black Rope that disrupts and cancels cursed techniques effects. Unfortunately and ironically, Gojo himself either sealed or destroyed the Inverted Spear of Heaven 11 years ago, and Yuta confirms that he, along with Miguel, searched for the Black Rope in Africa but to no avail. Tengen revealed the only other method available, that among the players participating in the culling game, there is a sorcerer from 1,000 years ago who calls herself an angel, and her cursed technique can extinguish other cursed techniques.

When Megumi asks about the location of Hana Kurusu, Tengen tells the latter that she is on the east side of Tokyo and says that they will begin their explanation here. Master Tengen explains how ten colonies all over Japan are connected by a barrier that forms a line that sends humans from Japan to the other side. Yuki asks if Hokkaido isn't included because of jujutsu society's barriers, confirming and adding that Hokkaido has already been established as a vast sacred land. Tengen includes that although conveyance to the other side may sound exaggerated, a curse fell on everyone in Japan in preparation for the merger. Megumi asks how long the ritual will take, and Tengen tells him two months will suffice.

Maki says that it's 9 a.m. on November 9th Yuta adds that player sorcerers awakened at about midnight on October 31st. Megumi concludes that Tsumiki only has roughly ten days and 15 hours to declare her participation in the Culling Game, and Tengen confirms that refusing to participate would be fatal. Maki says that what Ieirisaid was true, so that means sorcerers such as herself, who have no cursed technique, are unaffected. Yuji wonders about the civilians who are already inside a barrier where Tengen says they will be given a chance to exit, much to his surprise. Yuta comments on how generous of it of them.

Tengen then says there is no rule about entering or exiting colonies and adds that from the start, players are given a clear objective of exiting the barrier and that they suppose this is for stimulating the game. Tengen tells them that the premise that they entered their own volition is vital to confine the players. Yuji thinks about what Ino told him about the "increase or decrease" of a barrier's effectiveness. Tengen tells them that each player will receive a shikigami called a Kogane. Tengen adds that a Kogane is less a game master than an interface. They say they may think of the game master as the Culling Game programmer, which confuses Yuji. Yuji says they cannot subtract existing rules, while Megumi says there are ways to counteract them. Choso asks if the sixth rule is fair, which Yuta confirms, while Maki comments on how it gives the game master a lot of leeways.

Tengen informs them that the players are subjected to strict rules, and sorcery wise, Kenjaku is due to no other bias. Yuji is disappointed that he will be forced to kill people again, as Megumi tells him he has a few ideas. Maki tells them that's all the information they have, and now they all have a role to play with Yuki and Choso remaining as Master Tengen's guards. Maki says that she'll return to the Zenin Family and collect cursed tools. She reveals that soon after Satoru Gojo was sealed, the Kamo and Zenin family went to Tokyo Jujutsu High's cursed warehouse and completely emptied it. Maki also includes that Megumi is now the current Zenin family leader, much to Yuji's surprise. Maki adds that thanks to Megumi being the new family leader, it's possible to search the Zenin family's warehouse at length. She turns to Master Tengen and asks about Juzo Kumiya's warehouse.

Maki tells them that afterward, she will look for Panda and help address the game. She then turns to Yuta and asks what he will do. Yuta says that he will enter a colony immediately before Tsumiki Fushiguro is needed to enter the game. He wants to gain more information. He says he will avoid nearby colonies, so they won't kill each other, just in case something happens to Tsumiki. Just then, both Yuta and Yuji realize that Yuji asked Yuta to kill him if Sukuna ever takes over his body. Megumi assures Yuji that it won't happen and says that if it ever did happen and he dies, Megumi tells Yuji to have Okkotsu kill him. Yuji is angry by this as the point was not to let that happen. Megumi turns to Maki, who tells them to go to Kinji Hakari as planned, where Yuji is confused about who that is.

Yuta reveals that Kinji is a suspended third-year, as Maki tells them that because they're shorthanded, they will need to get as many people involved as possible. Yuji asks if they're tough as Maki says that he's moody, while Yuta tells him that when Kinji is worked up, he is stronger than himself, which Maki comments on how it's not true. Yuji, along with Maki, Yuta Okkotsu, and Megumi, start heading out before Yuji calls out to Choso and thanks him, who tells Yuji not to die. Tengen remains with Yuki and Choso as Yuki asks Choso if he's crying.