After a couple of days thinking it over, I believe I'm going to alter the Maria and Emma chapters.
Instead of having them trapped in another world, Maria accidentally summons a monster from another realm which runs off into the woods. Over the coming weeks, news spreads of a vicious, hairy beast killing young men and women throughout the region.
Sensing the mystical nature of this beast, Amalie rallies a hunt with Tera, Richter, Emma, and Maria, to find this beast and put an end to its rampage.
Maria is stricken with fear and immense guilt, and does not reveal the monster's possible origin until an attack separates her and Emma from the rest of their group. But they are being pursued, the monster summoned may not be what it seems.
I think this will work better and make the plotline flow easier without adding another universe entirely, and we'll get to see Maria and Emma work together.