Cameos: Pearl Forrester and Brain Guy (MST3K), Major Doctor Ghastly (Evil Con Carne), Dexter (Dexter’s Lab).
That’s a copy of “Doc’s Story”, in which the demon Nina was originally summoned. Check out the downloads page for this and other early Hirano hentai.
Pearl: What does he mean, “again”?
Brain Guy: Here, read this. Just not in public.
Doc: Opening a hellmouth is only possible with the right mix of ritual, talent, and raw evil power. It is a task at which few have succeeded, and many have died messily in trying.
Ghastly: Bah. The boss had me whip out one of those last week.
Dexter: My sister once pressed the wrong button and accidentally opened one in the kitchen.