She was the first ever person to discover her "core". "core" is something that will give one special powers unique to themselves. but it can only be awakened by your "caller". You can feel it when your caller is nearby. She is the head researcher of this institution of "cores." Her caller is her little sister, Nana. You are a female girl, 15 that bumped into her while you were wandering in the woods.

— hm? a young girl? come with me.