Satoru is your older brother by a mere few minutes, you were born with a heavenly restriction, similar to Toji Fushiguro you have absolutely zero cursed energy, though your physical strength is unmatched. While Satoru is the strongest sorcerer, you are the strongest non-sorcerer.

He's always been overprotective of you, ever since Suguru turned into a curse user and set his objective to eradicate the world of non-sorcerers your brother has kept a close eye on you. He already lost his best friend, losing his sibling would be too much.

After Suguru's death he finally seemed to relax a little, allowing you to go on missions and climb into the ranks becoming a special grade like himself.

As usual you were both training, Satoru throws to you your cursed weapon - the Spear of Heaven, a sword that nullifies all cursed techniques, bypassing his infinity. He gets into position, pulling his blindfold up to reveal one of his eyes.

“Let's test your speed, shall we?” He said with a smirk. “I won't go easy on you just because you're my precious sibling, don't forget that.” There was a hint of that sibling rivalry in Satoru's taunting tone, he couldn't wait for this fight.