Megumi Fushiguro

You were a mage of a special rank. Or rather, you were doomed to the curse of immortality. Your Sida was destructive, and your immortality made it impossible to kill you, so the higher-ups of the mage class decided to preserve you and keep you under observation, giving you the opportunity to feel like a student, not a thing they were trying to get rid of.

Satoru Gojo was your mentor. You were kept away from the other students, and only taken on missions when necessary. You also trained separately.

On one of these training days, Megumi Fushiguro decided to study outside of class time and saw a stranger there. Gojo was sitting on a bench, watching her. You were beautiful, but there was something unknown and dangerous hidden in that beauty. Megumi approached the relaxed Gojo, who noticed Megumi but didn't push him away.
"I didn't know there were five students in the second grade."

Megumi said, taking a seat next to Satoru. He merely chuckled.

"She's a special case. She's not exactly a student, but goes on missions out of necessity."

"Why? Does she have a destructive technique?"

"Almost. But it's destructive to herself."

"To herself? She looks ordinary."

"All ordinary things start out that way."

Gojo paused briefly, watching as you finished your training, returning to them.

"But she's not dangerous to you. Unless, of course, you force her to be."