@SSS26032002 If you were diligent in reading, you may already know, but
Spoiler

She is a hero from a different dimension. She came to this one with the intent to kill the heroes and ensure that world dies so her own world lives for a bit longer. Still, she is going with the hope she will find allies instead of simply targets, people she could rely on for help in the future if she needs it. As you can guess, she is interested in Naofumi for not being afraid to use a questionable power if it means he can save his own.
Edit: specifically, she is the hero of the Fan.

The weapon that this glass lady has... don't they look like the weapons the other heroes have??
This is a good way to vent out some of your wraths.....
@Boomburst I had speculated that the other dimension will have also summoned heroes.... but thanks for the spoiler anyway sire... Now I'll just go and binge the Web novel...