u/Cuneye669

Black flash is a cursed energy related phenomenon that occurs when cursed energy is applied within 0.000001 seconds of a physical hit. This amplifies the strength of one's cursed energy by 2.5 and causes cursed energy to flash black. This is harder to use on weapons but can be used to defeat opponents in a single strike.

There is a hidden secondary requirement of the user's body temperature reaching exactly 49.77°C (121.4°F). This only occurs within sorcerers in the heat of battle, as they would die if they were a regular human. The reason for the specificity is unknown, however it is theorized that it originated from the 49 days (7x7) of mourning. Due to these 2 requirements, Itadori Yuji is the only person capable of landing a black flash on command. He does this by manipulating his blood and body temperature to an exact point with the Kamo clans technique while using cursed energy within a millionth of a second.

After landing a black flash, a sorcerers body temperature automatically adjusts to remain at 49.77°C. Thus making black flash a test of skill rather than heat. This is referred to as 'the zone' by modern sorcerers or 'Bardo' by the old fashioned sorcerers and nearly all clan members. The intense heat causes effects on the brain that makes using cursed energy as easy as breathing. Being in this state or having memories of being in this state of Bardo dramatically increases one's ability to use cursed energy.

The reason why black flashes are created is a concept similar tunneling in video games. It is caused by an objects state only being 'checked' every 0.000001 seconds. Changing its state with cursed energy within that time causes a spatial distortion where the attack exists multiple times at once. The light from that also will become black.

Extensions:

Black central guard: A similar cursed energy phenomenon created when a sorcerer blocks an attack with cursed energy within 0.000001 seconds of an attack landing. This creates black sparks and increases durability by 2.5 for that attack. To activate the central guard, one must fulfill the first two prerequisites while not using a cursed technique. Due to the last requirement, even Yuji can not activate central guard at will.

White sparks: A technique activated when one tries to use reverse cursed technique to regenerate the body within 0.000001 seconds after being hit. This fully heals the body without wasting much cursed energy and is essentially random for the same reason as central guard. It is seen as a last resort during battle.

Blackout: The rarest jujutsu phenomenon occurs when two blackflashes land simultaneously. This creates two spatial distortions that slam into each other. It creates a large explosion that hits both participants and anyone nearby for 5 times the damage of the original attacks. Yuji can produce this phenomenon any time he wants and only takes partial damage to himself.

Blood manipulation is the main hereditary technique of the Kamo clan. Bone manipulation is less common then blood manipulation and lacks the powerful piercing blood attack. Instead, bone manipulation is a 'jack of all trades' technique that focuses on high offense and defense in close range. While blood manipulation reflects on the Kamo clans obsession with bloodlines, bone manipulation represents their rigid belief systems and the obsession with maintaining structure.

As the name suggests, Bone manipulation allows the user to control the bones on the inside or outside of their body when reinforced with cursed energy. Bone manipulation can change the physical properties of it's targets too.

Outside of the body:

The cursed techniques created from the Kamo clan can't create the target fir their manipulation. Instead the user must figure out a way to get more resources for technique activation. In this case the user must suppress inhibitors like SOST while boosting bone building genes like Wnt or LRP5. Then they can use cursed energy to increase the speed further outside of the body. Users of the technique can increase and decrease the size of bones outside of the body during ranged combat. Launching bones at opponents is the main way of ranged combat, but they lose strength when bones are shot in large volleys

Bones can be used for movement, growing under the feet of a user or to be used as bars to hold themselves up. Weapons can be made by sharpening the bones or staffs with extra long bones.

Inside the body: Since the bones inside the body are created naturally and are used in lower amounts, they are stronger. The user can manipulate the density of their bones when striking to increase force. Lighter bones will cause the bone manipulator to move with increased speed. Users often switch between light and heavy bones depending on the situation. Switching density on the inside usually takes a few seconds.

Extensions:

Brass bone knuckles: The user sharpens or hardens the bone in their knuckles until the appear outside of the body. The user has enhanced strength on their punches while this extension is active. Users without reverse cursed technique will be left with hand injuries.

Raise: The user leaves smaller bones around a battle field and typically hidden under other objects. The user can increase the size of the bones at any time to land surprise attacks from anywhere. This can be used with bones above targets too.

Splinter volley: The user shatters one of the bones use for manipulation. The shards are then shot at opponents the create many cuts. If the shattered bone was reinforced with cursed energy before being broken, this can bypass the lowering of cursed energy across the shards.

Falling bones emotion: By spreading bones across a large area in a diamond pattern and applying the secret art of falling blossom emotion, sorcerers are capable to automatically blocking any attack from any direction. This technique is most powerful when fighting several opponents at once.

Bone blaster: The user creates structures in the form of skulls that can be used to remotely fire blasts of cursed energy. Even those on the grade 1 level gains an increase in output to fire blasts on cursed energy. These are created using a binding vow that sacrifices the bone structures after one shot of cursed energy go increase output.

Clone creation: The user creates skeletons of themselves for a short time for combat. These skeletons can be used to create shikigami to fight together. They can be created with dense bones or light bones depending on the current needs of the user.

Supreme art: Decapitated walkers

Decapitated Walkers is a supreme art that creates shikigami in the form of small skeletal fish at the user's side with bones as a medium. The user can produce 10-13 of these shikigami at once to fly through the air at targets. Decapitated walkers have enough bite strength to reach an equal opponents bones and infuse them with cursed energy. Since the fish bite to the bone, this allows bone manipulation to bypass one's innate domain and take control of the bones. The supreme art is restricted to only manipulating the bones struck by the fish.

Domain expansion: Ocsilating structured requiem

The domain manifests as a large space with a large circular structure made of bones spins above. The ground is rough concrete and uneven in certain places. The sure hit effect strikes the target with bones from all sides. Some are sharp while others are blunt to create an effect that causes targets to be surprised each hit. While the regular sure hit won't typically kill immediately, the decapitated walkers can kill nearly instantly when activated.