Binding vows are considered by all jujutsu users to be one of the essential tenets of jujutsu sorcery. Binding Vows are essentially contracts created through cursed energy that an individual can make with one's self or another person. The act of abiding by the rules and restrictions agreed upon in these contracts can result in a greater power or the achievement of a goal, but breaking a binding vow has uncanny repercussions.[1]
Vows with Oneself[]
Self-imposed restrictions that are potentially harmful to the creator, such as willingly limiting the amount of cursed energy they can use for a period of time, can increase the amount of the user's cursed energy and of their cursed techniques.
As a product of negative emotions, cursed energy responds to the desires of its individual user. As a result, the user can increase the power of their cursed energy by stating a self-imposed "Cursed Restriction" that creates riskier conditions to use their abilities. For example, by divulging one's cursed technique, it creates more risk for them, making their cursed energy swell in response to its user's resolve.
In addition, creating rules for using one's cursed energy and abiding by those rules which allow their cursed technique to improve in strength. The penalty of breaking a binding vow with oneself is the loss of whatever was gained through the contract. [1]
Revealing One's Hand (情報の開示,Jōhō no Kaiji?): A Binding Vow that increases the user's cursed energy output in exchange for vocally divulging how their cursed technique functions.[2] Skilled practitioners can increase the effectiveness of their techniques as well as mislead their opponents on how it works.
Overtime (時間外労働,Jikangairōdō?): A Binding Vow used by Kento Nanami that limits the amount of cursed energy he can access to about 80-90% while on the clock working for Jujutsu High. Once his normal shift ends and he begins working overtime, Nanami's cursed energy increases dramatically.[3] By invoking Overtime, Nanami is able to utilize 110-120% of his maximum power.
Vows with Others[]
Contracts created between two or more individuals are bound by cursed energy. Both parties must agree to a particular set of conditions that benefit both parties. The penalty for breaking a Binding Vow with others is considered to be far greater than that of a self-imposed Binding Vow.[1]
When Yuji's body was deceased, Sukuna proposed a Binding Vow that would allow him to heal in exchange for allowing Sukuna to take control for one minute whenever he said a keyword, "Enchain" (契闊,Keikatsu?). He also promised not to kill anyone during that time on the condition that Yuji would forget about the vow.
Yuji initially refused and demanded a fight to death in response. As a compromise, conditions were set by Sukuna. If Yuji wins then Sukuna will revive him without the Binding Vow. If Sukuna wins, then Yuji must agree to the Binding Vow and will lose all memory of it. Sukuna instantly defeated Yuji, forcing him into the vow.[4]
After Yorozu reveals herself to Yuji and Megumi, Sukuna activates the binding vow by saying "Enchain" which grants him complete control of the body. Afterwards, he rips off one of Yuji's fingers and transforms it into a cursed object, force-feeds Megumi the finger, and transfers his consciousness into Megumi.[5]
A contract between Mahito and Kokichi Muta for Muta to act as a double agent for Mahito and Pseudo-Geto. Mahito agreed to heal Muta's body with Idle Transfiguration in exchange for cooperation and information, on the condition that Mahito would not "lay a finger on anyone from Kyoto Jujutsu High."
It is alleged by Muta that this contract is broken, but Mahito rebuts this point by stating that Hanami actually was the one who hurt the students from the Kyoto Jujutsu High. Muta is transformed by Mahito's cursed technique after acting as a double agent for presumably some time, which brings the contract to an end, although it is unclear whether or not there was a breach.[1]
Ui Ui has a contract with his sister Mei Mei where he agrees to limit his cursed energy until she gives him permission to use jujutsu. This stems from his own desire to please his elder sister.[6]
Kenjaku revealed that the cursed objects he provided for the sorcerers were what was left of the binding vow he made a millennial ago and reveals that he indeed did enter a contract with sorcerers but the binding vow broke after he obtained Suguru Geto's body.
At the end of the Shibuya Incident, he remotely casted Idle Transfiguration on non-sorcerers to adjust their brains for sorcery and give them strength as vessels. Later on, he broke the seal on the cursed object and incarnated thousands of sorcerers from the past to start the Culling Game.
In order to become Itadori's fake executioner, Yuta Okkotsu was forced into a Binding Vow with the jujutsu higher-ups where he was sworn to kill him. He then ends the Binding Vow when he does kill Itadori, but heals him with a reversed cursed technique in the very moment he does kill him, resurrecting him in a sense.