Gekiganger 3

When ancient cave paintings turn out to be blueprints for a giant robot, three high school kids must save Earth from an alien empire — and that's Gekiganger III in a nutshell — a loving, self-aware send-up of classic 1970s and 1980s super robot anime like Getter Robo and Mazinger Z, crammed into a single OVA runtime. Ken pilots the jet, Joe handles the marine craft, and Akira drives the tank, and yes, they smash them together into one giant robot to punch aliens. It hits every beat you'd expect from the genre it's poking fun at, but with its tongue planted firmly in cheek the whole time. The humor comes from how earnestly it commits to the tropes — dramatic combination sequences, over-the-top villains, noble high schoolers somehow being Earth's last line of defense. If you've seen Combattler V or anything from that era, you'll catch every joke. If you haven't, the setup is goofy enough to work on its own. Here's the extra layer worth knowing: Gekiganger III originally exists as a fictional show-within-a-show inside Martian Successor Nadesico, where the characters are obsessed with it. This OVA fleshes that out into a standalone piece. Whether you're coming from Nadesico or just want a short, comedic mecha parody, it delivers exactly what it promises.