With the 2nd stage of Jujutsu Kaisen afoot, we will expect to face many challenges and barriers put in front of the cast we know and love. Gege has planted seeds in the first stage to test the cast and force them to grow in the second stage.
Specifically, a character of interest that is connected to one of our main characters was affected by Brain's plan to introduce chaos into the Jujutsu Kaisen world and that person is Tsumiki, Megumi's sister and one piece who holds him together.
To recap, Brain wants to force the evolution of cursed energy by enabling individuals he has marked, people who he had ingest cursed object like Yuji and people who have dormant cursed techniques like Junpei, to fight and deepen their knowledge on cursed energy.
Brain has been setting up this plan for many years. Megumi was affected by this when his sister was marked when he was in his third year in Junior High. Tsumiki wasn't the only one though, people were marked on a Nationwide scale.
Brain has strategically hand-picked the individuals who he believes will be suitable for this chaos he has envisioned and surprisingly Tsumiki is one of the candidates that he has picked. This has had the community confused as to how Tsumiki could be a candidate for Brain's plans
Tsumiki was one of the types of sorcerers Brain talked about. I believe she is someone who Brain had ingest a cursed object. 1 because after Brain released the seal he stated that some of them have been in deep slumber ever since they were exposed to his cursed energy.
2 is a personal detail. Yuki asks the question WE ask regarding Tsumiki and it's if she will actually become malevolent. A question asking if Brain is underestimating human rationality. This question was shut down by Brain saying an oversight like that would not be made by him.
The Cursed Objects that Brain has provided is whats left of sorcerers he has "painstakingly" made contracts with, but then he says that he didn't just make contracts with JUST sorcerers which means that curses are also entities he may have made contracts with as well.
We know curses can make contracts/vows because we saw Mahito make one with Muta, better known as Mechamaru. A curse would have to be a high-level curse in order for this to be done.
Chapter 20 is the first time we get information about the brain being a mystery in its link to cursed energy. Coincidentally in chapter 136, we get closure on this mystery through Brain. The same image in chapter 20 is used in chapter 136. A very nice callback.
There's also a detail hinting at Brain knowing the mysteries of the brain and its connection to Cursed Energy but it's very subtle. I noticed it while rereading Shibuya and it has caught my attention ever since and was confirmed in chapter 136.
In this same chapter 20, Mahito states that an image of fear, whether it is real or not, can manifest into a powerful curse. The examples he poses are Hanako-san and the Nine-Tailed Fox (Kitsune). What is a better way to foreshadow these powerful curses in the story?
The Nine-Tailed Fox is a mythical fox in Japanese folklore possessing paranormal abilities and have the ability to shapeshift into human beings. Their paranormal abilities get stronger as they get older.
One thing that leads me to this connection with Tsumiki and the Kitsune is that after reaching 1,000 years of age a Kitsune would gain its ninth tail. 1,000 years is the number of years Brain has been on this grind of creating contracts.
Number 2, Kitsunetsuki which is also written as "kitsune-tsuki" means 'the state of being possessed by a fox'. Specifically, the victim is said to be a young woman. This phenomenon was described as a disease as early as the Heian period.
To add Kitsune tend to generally take form as a beautiful woman. In Medieval Japan there was a common belief that any woman encountered alone, especially at dusk or night, could be a kitsune.
This is a personal detail I noticed but "kitsune-tsuki" has "tsuki" attached to "kitsune" I'm not a Japanese expert by any means but tsuki and Tsumiki are very similar. This could obviously be a coincidence but I do believe that it's interesting to point out.
In Classical Japanese Kitsu-ne means "come and sleep" and "ki-tsune" means "always comes". This is related to a 'widley known' etymology in Japan relating to 'sleeping' and 'returning home'.
Third. Tsumiki always has very pure imagery around her. She always seems to be in the middle of a Garden when she is shown, a caretaker. Foxes even in real life, are animals that are a danger to the purity to a garden, especially in urban gardens.
In Chapter 59 you see Tsumiki lying down in the same Garden that is always behind her, except this time it's cursed, destroyed, and not as graceful as it has been in past imagery. She is the one lying in it cursed herself as if she is the one connected to its destruction.
Lastly, something I believe convinced me as I was reading up on this is that Kitsune have a fear and hatred of dogs. This fear would expose them and lead them to revert to their fox form and flee.
The one person in the story connected to dogs is Megumi. I believe that this is how the connection starts. The use of Tsumiki by strategically putting her against her little brother by giving her a cursed object that has a fear and hatred for dogs connecting to Megumi's CT .
Devout individuals are able to see through the Kitsune's disguise merely by perceiving them. Megumi is without a doubt a devout individual. His belief in his conscience is what drives him through his journey as a Jujutsu Sorcerer. He is totally committed to his cause and belief.
The 2 people connected to Megumi's path both being vessels and powerful sources of fear would be an interesting dynamic and it would connect back to what Megumi told Yuji all the way back in Chapter 6 to Yuji. These two are always seen when Megumi is talking about his conscience.
Megumi's conscience being tried in the future, his principles and ideals, is something we all expect to be tested in the future. The resolve that he believes in might be pushed to it's limits forcing him to develop just like how Yuji's resolve was being tested and he grew aswell.
There is a lot of speculation within this theory but I believe there are some valuable parts and connections. I just made this to enable discussion on what Tsumiki could be possessed by and how this could lead to a very heartbreaking conflict between the two siblings.