Demonbane OVA

In this strange metropolis, advanced technology and actual magic run side by side, which already sets the vibe pretty well. Kuro Daijuuji is a broke private detective scraping by in this strange metropolis when a young heiress named Ruri Hadou hires him to track down a powerful grimoire. He finds more than he bargained for — a girl named Al Azif, who turns out to be the living embodiment of the Necronomicon itself. Yes, that Necronomicon. The one H.P. Lovecraft wrote about. She's been on the run from a shadowy sorcerer syndicate called the Black Lodge, and the moment Kuro crosses paths with her, he's pulled into their world whether he likes it or not. The two form a contract, and suddenly this down-on-his-luck detective is co-piloting a massive mecha called Demonbane against genuinely eldritch threats. The tone bounces between goofy comedy and legitimately tense action, sometimes within the same scene, which takes a little getting used to but ends up being part of the charm. If you liked the mythological weight of Fate/stay night or the mecha-meets-metaphysics energy of RahXephon, this scratches a similar itch with its own weird Lovecraftian flavor. It's a single OVA, so the commitment is low, and the animation holds up well enough to make the action sequences feel worth it. Go in expecting something offbeat and it delivers.