This monster is "Gishki Noellia", infected by the "Evilswarm" virus ("Infestation Infection"), as shown in the artwork of "Creeping Darkness". However, compared to other infected monsters, "Gishki Noellia" is not completely corrupted by the virus, as her name remains unchanged.
The symbol of the "Evilswarm" can be seen on the chair-like structure that this monster is sitting on, the corrupted "Gishki Aquamirror" she is holding, and faintly on her torso.