Cursed Spirit

Cursed Spirits (呪い Noroi) are the manifestation and aggregate of Cursed Energy - "the negative energy that flows out of people" (Chapter 1; Chapter 20). As a result of the cursed energy flowing into particular notions or things, curses are born (Chapter 20). They harm humans, both civilian and sorcerer. Consequently, they are the primary targets of sorcerers.

Creation
When civilian humans think negative thoughts about something (e.g hatred, fear, or jealousy), the resulting cursed energy from those thoughts leaks out of their bodies. Curses tend to form in areas such as schools or hospitals where many people tend to have bad memories and feelings there (Chapter 1). The more people that have negative feelings towards the same thing, the more cursed energy is created and the stronger the resulting curse will be. For example, a curse born out of people's hatred for other humans would be very strong. Curses can form as a result of fear of the ocean, the forest, and the earth, as well as by deities of areas. They tend to form in areas where people have a lot of memories. Curses naturally form in this way.

Sorcerers collect cursed energy from their bodies and control its flow within their own bodies, rather than expelling it. Consequently, sorcerers leak a significantly smaller amount of cursed energy from their bodies, preventing them from being able to create curses in this manner. However, sorcerers can create curses where they are killed without the use of cursed energy (for example, being shot), and release their negative emotions when they die. To avoid this, sorcerers kill each other using cursed energy.

Characteristics
Curses are immune to conventional weaponry and are only able to he harmed or "exorcised" by Cursed Energy. Where a curse is too powerful to be exorcised, it will be sealed and stored away. Where a person is themselves cursed, they may be able to undo the curse by "finding each of the thousands of knots" of cursed energy and undoing each knot individually (Prequel Chapter 2).

Curses cannot be seen by civilians unless in “special conditions” such as life or death circumstances, but shamans can see them regardless (Chapter 1, Prequel Chapter 3). It is unknown why, but it is likely that this is due to the flow of Cursed Energy in a person’s body (Prequel Chapter 2).

Strong curses are more human like; they can become bipedal, sentient, and develop the intellect of a human. Only High-Grade curses have shown enough intellect to be able to speak human language. Curses are invisible to non sorcerers. They can be killed with normal weapons (e.g with a gun); releasing the curse's energy back into the environment. However stronger curses cannot be killed without curse energy.

It is also implied that shamans have more resistance to curses than civilians do, although this is somewhat contested. Curses have some kind of healing process or regeneration, although this is contested.

Curses also have souls, although it is unclear how this occurs (Chapter 49).

Curses are supposed to linger at their point of origin (Chapter 8).

The act of crossing rivers or crossing to the other side of something has deep significance for curses.

Some curses can place a “mark” on a person, which serves as a homing device - once activated, they will attack that person wherever they are (Chapter 56).

It appears that curses can have master-servant relationships with shamans, which can protect the curse from external threats. For example, Toji is said to have a master-servant relationship with the curse he stores in his stomach, which was why it repelled Getou’s attempt to steal it (Volume 9 Extras). It is unclear how this relationship is formed.

High Grade Imagined Apparition
Frightening imagery shared among many people manifests into powerful curses. Mythological creatures from stories can manifest, and become High Grade Imagined Apparition, where a significant amount of cursed energy is directed towards them (Chapter 20). The negative thoughts directed towards the forest, solid earth, the ocean, and other humans has resulted in the formation of High Grade Imagined Apparitions developing (Chapter 20).

Vengeful Spirit
Vengeful spirits are a certain type of curse. It is unclear what they specifically are, but they have unique characteristics compared to other cursed spirits. It appears that some form of master servant relationship is formed when they are created. Vengeful spirits appear to be created by the form of some kind of curse from another, although this is implied specifically towards Rika so it is unclear whether this is the case for all vengeful spirits (Prequel Chapter 4). It is theorised that they had to previously be human, but there is no evidence to support this theory as of yet.

Known Vengeful Spirits:
 * Rika Orimoto became a vengeful spirit after Yuta Okkotsu cursed her by accident when she was hit by a car and he did not want her to die (Prequel Chapters 1, 4). Rika was then attached to Yuta, although it is unclear whether this was due to the fact he had cursed her or due to their relationship (as they were very close and had promised to marry each other when they were grown up) (Prequel Chapters 1, 4).


 * The Gojo clan is descended from a vengeful spirit, Sugawara-No-Michizane, who in the jujutsu world was a famous shaman and “one of the three greatest vengeful spirits” (Prequel Chapter 4).  This has led to speculation that the three clans are founded from the three greatest vengeful spirits, but no further information has been given to provide support for this theory.


 * Suguru Geto also summons a vengeful spirit, “Tamamo-no-Mae’s Avatar” (Prequel Chapter 4). Tamamo-no-Mae in Japanese mythology is a spirit of a nine tailed fox who possesses people, typically women and consorts. We do not know if this relates back to an actual person in Jujutsu Kaisen canon as of yet.


 * It is theorised that Sukuna could be a vengeful spirit.

Special Grade Curse
Very strong Curse. Large explosives might work (Chapter 6).

Grade 1 Curse
Strong Curse. Will take more than a tank to kill (Chapter 6).

Grade 2 Curse
Can be killed with a shotgun (Chapter 6).

Grade 3 Curse
Can be killed with a pistol (Chapter 6).

Grade 4 Curse
Can be easily killed with a wooden bat (Chapter 6).

Traits/Idiosyncrasies

 * Most weak curses attach to a person, and cause them great discomfort (i.e. heavy shoulder, trouble breathing, nightmares).Tokyo Metropolitan Magic Technical School: Chapter 3
 * Curses are Invisible to non-curse users. Unless in “special conditions” such as life or death circumstances.
 * Curses allegedly tend to linger at their point of origin.
 * It is also implied that shamans have more resistance to curses than civilians do, although this is somewhat contested.
 * Curses have some kind of healing process or regeneration, although this is contested. * Curses also have souls, although it is unclear how this occurs.
 * The act of crossing rivers or crossing to the other side of something has deep significance for curses.
 * Some curses can place a “mark” on a person, which serves as a homing device - once activated, they will attack that person wherever they are.
 * Curses are immune to conventional weaponry and are only able to he harmed or "exorcised" by Cursed Energy.
 * If a curse is too powerful to be exorcised, it will be sealed and stored away.
 * If a person is themselves cursed, they may be able to undo the curse by "finding each of the thousands of knots" of cursed energy and undoing each knot individually.