Ryukan: Beyond the Mirror

Have you ever run into someone you've never met, but they seem to know all about you? Either they're a stalker, or they're hiding something. After 18 year old Yuni bumped into Mamoru, this is exactly what happened.
As if having her studies weren't enough to worry about, now she has to worry about an entirely different dimension, and all the monsters and people that inhabit it. She could leave if she wanted to, but if she did then her own world would collapse. To make matters worse, since coming to this new world, Yuni has begun acting strange and, for no reasonable explanation, has blacked out on numerous occasions. Is it the effect of this world? Or is it just her? Perhaps it's both.
Can Yuni get along with these strangers she's met and save both worlds? Or do these instances of blacking out do more harm than what it seems?