Viper GTS

When a socially awkward guy cracks open an ancient text, tries to summon a demon for revenge against people who wronged him, and accidentally ends up with a blue-haired succubus developing feelings for him instead — that's the setup for Viper GTS, a 3-episode OVA that leans hard into its supernatural premise while making no apologies for what it is. Carrera is a demon whose job is straightforward: grant a human's wish, take their soul, move on. But Ogawa throws a wrench in that routine by being genuinely interesting to her rather than just another transaction. Meanwhile, her partners and rivals Mercedes and Rati aren't sitting on the sidelines, and the angelic side of this whole cosmic arrangement starts pushing back too. The demon-versus-angel politics give the show a bit more structure than you might expect. The vibe sits somewhere between the wish-granting mythology of Ah! My Goddess and the more explicit supernatural territory of something like Bible Black — so if either of those sounds familiar, you already have a rough sense of what you're getting into. The character designs are distinctive and the animation holds up reasonably well for a 2002 OVA. This is unambiguously adult content, adapted from a visual novel, so go in with clear expectations. It's not trying to be high drama — it's a short, self-contained supernatural romp with some genuine personality in its lead characters and enough mythological flavor to keep the world feeling like more than just a backdrop.