Cursed energy is born from negative emotions such as grief and anger. These negative feelings are common in human society so almost everyone possesses cursed energy. If this amount is higher than a certain degree, it grants the person the ability to see curses, which is very rare among the human race.
Curses are apparitions manifested entirely from cursed energy. Even their bodies are composed of cursed energy, making cursed spirits invisible to non-sorcerers. Jujutsu related items such as cursed tools, cursed objects, and cursed corpses all contain cursed energy.
The emission of cursed energy from humans collects like sediment until a cursed spirit is born from the collective negative energy. Curses born with strong feelings directed toward a certain aspect are especially strong. The stronger humanity's fear and anger is directed at cursing a certain aspect of the world, like natural disasters, the more powerful curses spawned from those negative sentiments will be.
Cursed Energy Detection
Humans with an above-average level of cursed energy can see curses and jujutsu. The minimum requirement for a human to be considered a sorcerer is the ability to see curses. In extreme cases, humans will gain the ability to see curses when their life is in danger.
Using jujutsu leaves residuals of cursed energy behind. Residuals leave spectral footprints that can be used to track the user. Someone can even be identified by the residuals from their jujutsu. Expert sorcerers can be trained to cover up their residuals. The ability to detect cursed energy and understand its flow can be honed, but many cursed spirits are capable of hiding their presence the same way a sorcerer does.
The strength of a sorcerer or curse is generally assessed by their levels of cursed energy. Strong cursed energy can result in physical pressure that instills fear into those who sense it as a method of intimidation. This is one way someone can assess the general level of power based solely on cursed energy. The same concept can be applied to a jujutsu battle. Reading an opponent's cursed energy is an effective way to predict their next move and keep track of their location. Prediction based on cursed energy can backfire when faced with a fighter in cases where a fighter's physical prowess outclasses their cursed energy. Physically fast and strong fighters with low cursed energy are often unpredictable to enemy sorcerers.
Sorcerers can also notice small, vague differences in cursed energy. Suguru Geto, a curse manipulator who must consume curses, has altered cursed energy more associated with that of a cursed spirit. The Inverted Spear of Heaven possesses foreign cursed energy that can cancel out jujutsu.
Cursed Energy Manipulation
Controlling Cursed Energy
A jujutsu user's ability to control their cursed energy and use it to carry out certain functions is the base foundation for all jujutsu. There is a world of difference between being able to sense jujutsu and being able to use it. Yuji Itadori was able to sense the pressure of cursed energy surrounding his school, but was not able to utilize it until enrolling at a jujutsu educational facility. He was first able to utilize cursed energy in combat while he was overwhelmed with anger and fear, but could not do so in a calmer situation a few days afterward.
Control over cursed energy requires innate skill and vigorous training. In order for Yuji to develop his skills, Gojo had him undergo special training that saw him controlling his emotions and his cursed energy at the same time. Yuta Okkotsu, someone with an overabundance of cursed energy, was trained to control it by constantly imbuing it into a katana. By training with the katana Yuta learned to manipulate his cursed energy to a degree and was capable of using it to exorcise curses almost immediately.
Satoru Gojo compares cursed energy to electricity: it's volatile in nature and difficult to use in its rawest form. While raw cursed energy can be used for its blunt force, it's best used by sorcerers to power their techniques in the same way electricity is best used to fuel electronics. In this case, cursed energy is flowed into a technique to activate a sorcerer's unique abilities. However, cursed energy does not flow on its own. Yuji Itadori's cursed energy used to lag behind his superhuman speed when he threw a punch, resulting in his Divergent Fist technique. This delay was due to his inexperience with making cursed energy flow properly throughout his body.
Proper control over one's emotions is key to channeling cursed energy and every jujutsu sorcerer is trained to do so. This makes it so sorcerers don't waste their power supply even while they're overcome with emotion. This results in sorcerers leaking much less cursed energy than the average human. So much so, that if every human were a sorcerer, curses would cease to spawn. There are other differences in how sorcerers and non-sorcerers use cursed energy due to their profession, but the real reason lies in how it flows. While cursed energy leaks outward from non-sorcerers, it flows heavily within sorcerers which keeps it contained.
Most sorcerers have to make cursed energy flow, so most instinctively believe it starts from the negative feelings in their stomach and flows through the rest of the body. However, thinking of one's body as different sections is what delays the flow of their energy. In order to understand this cycle, one must realize that they exist in the world with their entire mind, body, and soul as one. Aoi Todo helped Yuji stop taking this maxim for granted, greatly accelerating his progression as a sorcerer.
The flow of an elite jujutsu sorcerer is difficult to read because they have greater accuracy in controlling cursed energy. Their cursed energy is evenly distributed across their body, making their attack hard to predict until the very moment it's executed.
Applying Cursed Energy
Applying cursed energy to physical attacks can be as effective as a cursed technique when it comes to gifted combatants who prefer close quarters. Yuji can fight on par with that of a grade 1 sorcerer without a technique due to his seemly union of cursed manipulation and physical prowess. Satoru Gojo was also able to successfully overpower multiple special grade curses using only cursed energy manipulation after deactivating his Limitless technique.
Powerful cursed spirits can utilize raw cursed energy as an explosive energy field to attack. The Finger Bearers that Yuji and Megumi battled could launch their energy as a projectile and erect cursed energy barriers.
Defensively, users can coat their skin in cursed energy to harden their body and increase their ability to block incoming curse related attacks. The same application can be used offensively, imbuing physical attacks with cursed energy to increase their destructive power to superhuman levels. Aoi Todo crushed a curse, several trees, and broke through Yuji's defense with a single cursed energy infused punch.
Conventional weapons can also be infused with cursed energy to increase their strength. Imbuing too much cursed energy at one time to a normal weapon can compromise its integrity and destroy it, so a sorcerer must only infuse small amounts of energy at a time. Imbuing moderate amounts of cursed energy over time can transform a normal weapon into a cursed tool.
- Main Article: Black Flash
Black Flash is a phenomenon of jujutsu where a spatial distortion is born as a result of the application of cursed energy within 0.000001 seconds of a physical hit. The distortion causes cursed energy to flash black, multiplying the destructive power of a normal hit. There is no sorcerer who can use it at will, but those who have unleashed Black Flash gain an advanced understanding of cursed energy far beyond those who have not.
Reverse Cursed Energy
- Main Article: Reverse Cursed Technique
Cursed energy is born from negativity, so human flesh can't be regenerated from it even if it can be reinforced. By multiplying negative energy together, positive reverse cursed energy can be created. This can only be done using a reverse cursed technique, which requires extremely complex and sophisticated cursed energy control.
Vows and Risk
Alongside emotion, risk is a key factor that can affect cursed energy. The greater the risk to the user, the more their cursed energy will react. It is believed that the fastest way to raise one's level as a sorcerer is a Binding Vow with their life as the trade off. Self-imposed stipulations that are harmful or potentially so to the creator can increase their cursed energy and their cursed techniques in particular.
For example, the rules of a cursed technique establish the general parameters of an ability, and the activation requirements which determine the circumstances in which said ability can be used. By willingly divulging these rules, the user incurs more risk to themselves. Due to the negative emotions induced by potential repercussions, cursed energy grows in response and makes the cursed technique more effective.
This concept also applies to why normal humans can suddenly see curses in a life or death situation. Human senses are heightened when their life is in danger because of the instinctive fight or flight reflex. The same concept amplifies someone's ability to sense curses. A normal human's cursed energy will rise if their life is in danger of being cursed, allowing them to perceive it.
A jujutsu practitioner can increase the overall power of their individual cursed techniques by self-imposing further restrictions that force more conditions on the user. Kento Nanami's pact restricts the amount of cursed energy he uses while on the clock at work. Once his overtime begins, Nanami receives an influx of cursed energy much greater than he would have had if he didn't restrict himself. Mei Mei's Bird Strike forces a crow to commit suicide with its cursed energy limiter being removed as a tradeoff, resulting in a much more powerful attack. The effective range of Sukuna's Malevolent Shrine can be increased by including a Binding Vow that creates an escape route.
Applying conditions to abilities to increase their effectiveness goes for barrier techniques as well as innate techniques. By going against the fundamentals of casting barrier techniques and staying outside their own curtain, the caster increases the risk of being noticed and increases the barrier's strength. The more obvious the caster's location, the stronger the barrier.
There are a few cases of Heavenly Restrictions that reduced someone's cursed energy to low levels with increased physical attributes as the trade off. Toji Zenin's Heavenly Restriction in the only one in the world that eliminates cursed energy from his body completely in return for unparalleled superhuman strength, speed, and senses. The opposite, trading physical health for cursed energy is also true. Kokichi Muta was born with a fragile physical body and was given expansive cursed energy that spans a wide range in return.