The sexual attraction to monsters is known as Teratophilia.
Rohe's species is listed as "Ogre" in game despite her appearance obviously matching the "Oni" subspecies. This may be because, in Japanese mythology, "Ogre" and "Oni" are the same creature, and so Rohe was made an "Ogre" (ie "Oni") by the producers of the game without knowledge that the species "Ogre" and "Oni" were set as two different species in the manga/anime universe.
While Saki's race type is defined as "Elder Devil", she constantly states in-text that she is a Succubus. Due to the species of Succubus not being defined as a separate Devil subspecies by the manga at the time of the game's creation, it can be presumed that an Elder Devil, in the game world, is a Succubus.
