Radio

Radio is a doll created by Promestein appears in Chapter 3 and Paradox.

Monster Girl Quest trilogy
In Chapter 3, if Luka surrenders to Promestein in the Monster Lord's Castle, he is taken to the Drain Lab, where Radio rapes him using various machinery all over his body. This rape scene is added to Promestein's first Monsterpedia entry as "Rape Scene 2" and is required to complete the Monsterpedia.

According to Torotoro's blog, when the Drain Lab was destroyed after the self-destruct order, Radio was buried, still functioning beneath the remains of the destroyed Drain Lab, waiting for someone to dig her out.