Counter Dungeon-Delving

The people of the alpha plane have made it their hobby to enter the dungeons of other worlds and conquer them. Naturally not everyone is happy with this as dark undercurrents begin to work against the conquerors.

As some people die in the dungeons they are made an offer. To give up their humanity in order to live on.
Guy, a veteran carrier, is one of them, he can't bear to leave his family alone and accepts. From then on he must fight in the dungeons but as a monster while simultaneously continuing his life in the alpha plane in the shape of a human.
Jade, an elite adventurer, also accepts the offer but her intent is solely to get revenge on those who killed her and make humanity suffer for her life.
Monica, a little girl not native to the alpha plane is pulled into the happenings due to her childish innocence.