The MC will not know about it because the girls will keep it secret from him, just for plot convenience you know... This is why I hate this hidden power/true identity in mangas, is too out of logic. It's like they think it'll work like Batman or Superman.

Nevermind, it was in the 2nd ch and the eyes color are different. It seems like the artist is recycling character models...

I am curious, isn't this girl the same one who got killed in the first chapter along with the MC?