Un'Ichi Diaz (JJK Sona)

A fanatical fatalist, absolutely determined to carry their own will by believing it as inevitable.
"Risk? Risk implies uncertainty. There's no room for uncertainty in my world."

    Their cursed technique is based on promises and how they're kept. Behaves similarly to "Revealing One's Hand", but with the potential to be applied to all of the user's actions. Born with low (but still above that of a non-sorcerer) cursed energy, exchanged for heightened physical ability. They have to rely on their cursed technique to first gather it enough for it to be properly used. To activate its effect, they must describe the plan of actions they're about to carry out, with a higher effect payout the more detailed and exact the statements are. By perfectly carrying out the actions as exactly as described, cursed energy is boosted, amplifying its outcome (such as by damage dealt or mitigated) and/or granting a bonus surplus to be used for subsequent actions. In the rare case a plan is failed to be carried out, they try and try again no matter what, executing it sooner or later.
    Their domain expansion [Hall of Succumbed Spirits], coupled with its intrinsic sure-hit feature, renders them unstoppable, bending reality itself to allow for whichever fate they believe in to unfold. Due to the vast amount of cursed energy required from an user with hardly any, it can only be conjured by the end of long dragging fights as a last resort which ensures victory against any and all odds. When conjured, the domain takes the shape of an infinitely stretching, narrow corridor with a high ceiling and gothic architecture, reminiscing of cathedral interiors.

   The sword they carry, dubbed "Faith", was just a regular one which eventually became a cursed tool, as the energy they mastered throughout the years seeped its way into the blade, but it was only upon tasting utter defeat which it truly became cursed and awakened, much like its sorcerer proprietor. The now "Shattered Faith", despite being broken in half, serves as an external battery of negative energy, being able to leech it off opponents and reshape it into a new, immaterial blade of pure negativity, striking directly at the soul as no contact is made with the physical body. Despite its power, it dissipates upon each hit or parry, little by little, having to constantly be recharged for continuous use, eventually taking a toll on its own user if they're not careful.
   And Diaz, not too differently from their blade, broke in the same night as it. Knowing a defeat so crushing like never before led them to reevaluate their own pride and mind; the arrogant brat of so many years, always full of themself, had become consumed by a hatred of all else that stood between them and the pedestal of supremacy they so craved. The raging fire of youth had waned, giving way to a cold and calculated heart that certified Un'Ichi to never again know loss.