A simple difference of his death, a simple thought that changed his mind, and the simple omission of a person led to a world of difference. Not that he would've known the difference, and not like he would've given up what he had now for a world where he'd not made those decisions and mistakes. Kazuma knew that he would never give any of this up. He wouldn't, no matter what.

A variable, no matter who or what it is, will always change the results of anything when introduced. Be it a trivial equation or even the entire world, the undeniable truth was that as long as the variable had a value, it would change the things around it. Therefore, Nepgear knew that her existence and her sword would change this new world no matter what. She just didn't know how.