Ui Ui

Ui Ui works as a free, unaffiliated first-grade jujutsu sorcerer alongside his older sister Mei Mei.

He is introduced during the Shibuya Incident arc, attached to her as a dedicated support sorcerer.

His defining trait is an overwhelming, almost obsessive love and loyalty toward Mei Mei.

He considers himself her “property” and shapes both his technique and his way of life around serving her.

Ui Ui’s technique allows him to teleport people and even souls over extremely long distances.

He also uses the Shin Shadow Style “Simple Domain,” acting as Mei Mei’s primary countermeasure against enemy domains.

During the Shibuya Incident, he joins the Mei Mei team with Mei Mei and Yuji Itadori.

Later, in the Shinjuku Showdown, he plays a key role in soul-swapping training and helps rescue the wounded during the battle against Sukuna Ryoumen.

Affiliation: Free / unaffiliated first-grade jujutsu sorcerer

Family: Much younger brother of Mei Mei

Alias: “Ui Ui” is a false name, just like his sister’s name “Mei Mei” is also an alias

Gender: Male

Voice Actor (anime): Yuko Sanpei

Personal Data

Hobbies / Special Skills: Schedule management (specifically Mei Mei’s schedule)

Favorite Food: Pisang goreng (grilled or fried banana snack)

Disliked Food: None (he refuses to leave food uneaten in front of his sister)

Biggest Source of Stress: Being unable to stay with Mei Mei

Ui Ui’s personality is completely centered on Mei Mei.

He addresses her respectfully as “Sister” and treats her like an absolute object of worship.

He is thoroughly besotted with her, to the point that her stock phrases and cool one-liners make his heart race.

His love is not casual admiration but an intense, all-consuming devotion.

When Satoru Gojo has Mei Mei act as backup rather than a front-line fighter, Ui Ui remarks that making his sister play support is “a crime.”

To him, Mei Mei’s value is so great that any perceived slight to her status or role feels unforgivable.

Ui Ui once comments that what Mei Mei “cherishes” is not family, but the idea of “family as employment.”

Despite this rather cynical-sounding remark, Ui Ui is in fact her genuine, blood-related younger brother, not an adopted child or unrelated subordinate.

His wish to be “Mei Mei’s property” is not metaphorical.

He literally structures his technique’s conditions so that he cannot use it without her permission, making his existence and power dependent on her.

Overall, he is polite, composed, and eerily calm, yet the intensity of his feelings makes him stand out among the series’ many eccentric characters.

He is simultaneously a capable professional sorcerer and an extreme sister complex taken to its logical, frightening conclusion.

Ui Ui is not a front-line brawler but a high-utility support sorcerer.

His teleportation technique and Simple Domain make him indispensable in both combat and transport.

Binding Restriction with Mei Mei

Ui Ui’s jujutsu is limited by a deliberate self-imposed binding vow tied to Mei Mei.

He cannot activate his technique without a specific password from her.

Mei Mei must say the phrase equivalent to “I’ll stake my life on it” for his technique to activate.

This functions as a binding restriction that boosts the power and reliability of his ability.

However, it is more than a technical choice.

Ui Ui himself wants to exist as Mei Mei’s possession, so tying his power to her words fulfills his own deep-seated desire.

This combination of psychological devotion and jujutsu rules turns his technique into something unique:

A powerful, long-range teleportation cursed technique that literally cannot exist apart from Mei Mei’s will.

Cursed Technique: Target Spatial Relocation (Unnamed)

Ui Ui’s primary cursed technique is an unnamed ability that relocates targets through space.

He can teleport himself, other people, and even swap souls, provided certain conditions are met.

He can jump to locations or people he has previously marked.

This “marking” allows him to teleport with high accuracy over enormous distances.

The effective range of his technique is immense, demonstrated by teleportation from Shibuya in Japan all the way to Kuala Lumpur in Malaysia.

This places his range far beyond typical battlefield repositioning, making it a strategic-level transportation ability.

When activating the technique, Ui Ui covers the target with a cloth, reminiscent of a magic show illusion.

Once the cloth is drawn aside, the target has been relocated to the selected destination.

Consent and Soul-Level Operation

Ui Ui’s technique treats the body and soul as separable targets.

If the person involved gives explicit permission, he can swap souls between bodies.

In other words, two individuals can have their souls exchanged while their bodies remain physically unchanged.

Unlike Mahito’s Idle Transfiguration, these soul swaps do not deform the body’s physical shape.

Because of this, his technique is exceptionally useful for training, infiltration, or rescuing allies whose bodies or positions are compromised.

It introduces highly flexible tactical options without the grotesque side effects seen in other soul-related techniques.

Shin Shadow Style: Simple Domain

Ui Ui is a practitioner of the Shin Shadow Style “Simple Domain.”

This technique generates a small, simplified domain that acts as a countermeasure against enemy domains.

By deploying Simple Domain, Ui Ui can neutralize or mitigate the effects of a full “Domain Expansion” aimed at him or nearby allies.

In practice, this means Mei Mei can fight without worrying about being overrun by an enemy domain.

His Simple Domain forms a defensive shell or barrier that rejects an enemy domain’s automatic-hit rules.

This allows his team to survive battles they would otherwise lose in an instant.

The synergy between his Simple Domain and Mei Mei’s offensive power makes them a highly efficient duo.

Each covers the other’s weaknesses, and their combined effectiveness depends heavily on this complementary relationship.

Shibuya Incident

Ui Ui first appears during the Shibuya Incident.

He joins Mei Mei and Yuji Itadori as part of the “Mei Mei squad.”

His primary role is to support Mei Mei in combat by providing domain countermeasures and strategic teleportation.

By standing ready with Simple Domain and his teleportation technique, he ensures Mei Mei can fight at full strength.

Despite his young age, his calm demeanor and professionalism stand out.

He stays composed under pressure, placing Mei Mei’s safety and objectives above all else.

Shinjuku Showdown and Training

Before the final battle in Shinjuku, Ui Ui’s soul-relocation ability becomes central to a training regimen.

He uses his technique to perform “swap training,” exchanging souls in a controlled way to help allies improve and adapt.

Because his technique can move souls without deforming the body, it allows for unique forms of practice and coordination.

This leads to unusual training scenarios that would be impossible with conventional means.

Battle Against Sukuna Ryoumen

During the confrontation with Sukuna Ryoumen in the Shinjuku Showdown, Ui Ui shifts into a pure support and rescue role.

He works alongside Kirara Hoshi to retrieve and evacuate injured sorcerers from the battlefield.

His teleportation makes it possible to quickly extract wounded allies from lethal danger zones.

This logistical support is critical against an overwhelmingly powerful enemy like Sukuna, where survival and repositioning can decide the battle.

Ui Ui and Mei Mei function as a tightly synchronized unit, both emotionally and tactically.

Their bond is the core of Ui Ui’s character and his entire fighting style.

Mei Mei is a powerful, money-obsessed sorcerer who treats almost everything in terms of cost and benefit, including “family.”

Ui Ui openly acknowledges that what she “loves” is not family in a sentimental sense, but “family as employment.”

Despite that, he is her true, blood-related younger brother, not a hired child or unrelated subordinate.

He accepts her worldview completely and chooses to define his own value by how much he can serve her.

His binding vow that requires her “life-staking” phrase to activate his technique is both romantic and tragic in its extremity.

He insists on being something she uses—her tool, her property, her trump card.

It is precisely this willingness to belong wholly to Mei Mei that amplifies his cursed technique.

By entwining his heart, identity, and abilities with her, he becomes an exceptionally powerful and reliable support sorcerer.