Is Mei Mei and Ui Ui’s Relationship Toxic in JJK?

Summary

• A significant age gap between Ui Ui and Mei Mei hints at complex relationship dynamics.
• Ui Ui’s willingness to sacrifice himself showcases an intense devotion to Mei Mei.
• Mei Mei and Ui Ui’s binding vow highlights a symbiotic relationship based on trust and power exchange.

The following article contains spoilers from
Jujutsu Kaisen’s
Shibuya Incident story arc:

• Manga:
• Anime:
  • season 2, episode 38, “Fluctuations”

In Jujutsu Kaisen, Mei Mei and her little brother Ui Ui share a tight bond. The Shibuya Incident sheds plenty of light on the pair’s relationship. However, the most striking discovery is that Ui Ui would willingly give up his life for Mei Mei. Is this sibling relationship normal, or is it one of the most toxic relationships in Jujutsu Kaisen?

There are several layers to investigate. Age must play a role. After all, Ui Ui, a child, appears significantly younger than his adult sister. Mei Mei’s allegiance to money is also troubling. However, Ui Ui’s dedication to Mei Mei plays a vital role in his powers as a sorcerer. So, perhaps the two’s bond is something beyond understanding.

There Is a Significant Age Gap Between Ui Ui and Mei Mei

One of the first things JJK fans may notice about Ui Ui and Mei Mei is their age gap. Gege Akutami’s Jujutsu Kaisen Official Character Guide conceals both of their ages. However, Mei Mei had already graduated from Tokyo Jujutsu High in the Hidden Inventory/Premature Death arc, which takes place in 2006. So, she was at least in her early thirties during the Shibuya Incident in 2018.

Meanwhile, Ui Ui is not a student at Tokyo Jujutsu High, having first appeared with Mei Mei during the Shibuya Incident. So, one would suspect he’s at least middle school-aged (12 to 14 years old). That leaves an age gap of about 15 years between him and Mei Mei.

A fifteen-year age gap can undoubtedly lead to unhealthy behavioral dynamics, especially between a brother and sister. Ui Ui, a pre-teen, clearly puts his adult sister on a pedestal. That’s why he would not accept any criticism or dissent from Yuji toward her during the trio’s descent into the Shibuya subway station.

Ui Ui and Mei Mei’s Confrontation With the Smallpox Deity Has a Disturbing Twist

The Younger Brother Pledges to Die for His Adult Sister

There’s nothing wrong with a younger sibling looking up to their older sibling. However, traditionally, the older sibling is responsible for setting a good example for their younger sibling. Furthermore, one would expect Mei Mei, the adult sibling, to do everything she can to protect her pre-adolescent sibling.

Ui Ui and Mei Mei’s relationship reveals its darker colors during the duo’s battle with the special-grade cursed spirit, Smallpox Diety. Once she discovers that the spirit targets the most potent source of cursed energy, she asks Ui Ui a chilling question:

Are you willing to die for me?

–
Jujutsu Kaisen
, chapter 102

Any adult asking a child to die in their stead is a morally reprehensible request. When that child is your brother, the request feels more heinous. Surprisingly, Ui Ui enthusiastically agrees, “It would be my pleasure if you’d allow me to, sister.”

This exchange was likely the ‘something’s not right’ moment for many JJK fans. Akutami established Mei Mei’s transactional view of relationships early in the series. But using her brother as collateral damage passes into a realm of narcissistic abuse any sane person would not tolerate.

How could Ui Ui consent to death at such a young age? Was he brainwashed? Where the heck is Child Protective Services?

Ui Ui’s Cursed Technique Stems From His Devotion to Mei Mei

The Siblings’ Binding Vow Is Symbiotic

Ui Ui’s sacrifice turned the tables in the siblings’ favor against the Smallpox Deity. The younger brother nullified the cursed spirit’s technique with a Simple Domain, allowing the older sister to assault it with her cursed crow’s Kamikaze Bird Strike. Thus, the duo exorcised the formidable cursed spirit.

From an objective perspective, Ui Ui’s sacrifice resulted in a net positive outcome. Not only did Ui Ui help exorcise a highly dangerous cursed spirit, but neither he nor Mei Mei perished.

Did Mei Mei expect to cash in on her brother’s high-stakes gamble? Was it all a bluff? How can one justify this kind of decision-making?

Jujutsu sorcery relies on cold logic since most missions result in some loss, whether a normal human or sorcerer. Perhaps Mei Mei assumed that if her brother died, a more capable sorcerer (herself) would still have a fighting chance against the Smallpox Deity. And if Mei Mei died, Ui Ui’s death would be inevitable, and the special-grade curse would roam free.

While all of these points of consideration are valid, the reasoning for Ui Ui’s sacrifice is much simpler. Ui Ui shares a binding vow with Mei Mei. The condition of the vow is that he may only use his cursed energy with her permission. In exchange, Ui Ui can access high levels of cursed energy. How much? Enough to nullify the attack of a special-grade cursed spirit!

Binding vows are pacts a jujutsu sorcerer makes
with themselves or someone else. By following the rules and restrictions of such a pact, the sorcerer can access greater power or achieve a challenging goal. Breaking the pact incurs negative consequences.

Ui Ui’s binding vow with Mei Mei levels the playing field of their relationship. In return for putting his life on the line, he gains significant abilities for fighting within domains, a skill Mei Mei lacks. In short, she needs him as much as he needs her.

To sum up, many dynamics in the jujutsu world do not make sense to average humans. Us normies may consider Ui Ui and Mei Mei’s relationship toxic. And maybe there are some emotional obstacles that adult Ui Ui will have to work out in therapy. Or not. Regardless, Ui Ui and Mei Mei’s current bond works for them. We don’t have to understand it, but we should respect it.