Background:
Yuji Itadori is the perfect Mix of Human-Oni-Dead Apostle.
His father was a Dead Apostle Magus who wanted the perfect body while his mother was a half-Oni whose lineage could be traced all the way back to Ryomen Sukuna who was an Oni-Noble that eventually became worshipped as a Calamity God.
Sukuna's special technique has never once manifested into any of his descendants until Yuji's father managed to mysteriously acquire the fingers of Sukuna's. Which had become objects of incredible mystery and sealed them inside Yuji when he was born (Sukuna's consciousness isn't in them)
The Dead Apostle bloodline inside of Yuji was overwhelmed by his Oni Bloodline and as such he does not have 100% of the bloodline's full capabilities but is able to use some of it.
Holy Objects, Weapons, and Sacraments will have a certain degree of effects on him.
Yuji's mother upon discovering her husband's real intention hid their baby son with her father and fought her husband off before they both ultimately perished killing each other.
His grandfather moved them to Fuyuki City where Yuji would later end up becoming a victim of the 4th Holy Grail War and awakening his powers.
Future Powerset/Natural Abilities:
Yuji inherits a trait similar to Death Resistive Body comparable in principle to SHIKI's ability.
He can: Reshape Damaged Tissue, Crystallize and Control his blood, and Temporarily fight without vital organs.
Like some Oni Yuji has a unique pair of mystic eyes that allow him to see/perceive the boundary between the body and soul.
Said blood has a poisonous like trait to it due to his Dead Apostle bloodline.
Possess incredible physical strength, reflexes, speed, agility, sight, and nose.
A potent level of healing to the point an organ or limb can be regenerated.
Gains a bigger power boost when under a lunar cycle but during a new moon he remains mostly the same.
He possesses the inherited special power of Ryomen Sukuna and when properly trained could make Yuji a threat equal to or higher than Sukuna. OR less depending on the whole BS rules of the Nasuverse and Gaiya + Alaya's bs to.
Due to his complex nature Yuji has a high possibility of developing a reality marble...or at least something similar to it.
He physically stops aging once he becomes 25 years old.
A BLACK FLASH is impossible to do, to distort space is on the level of a True Magic or a Grand Ritual...but due to his circumstance only he is the sole exception to this. In other words I am pulling some BULLSHIT!!