Tenchi Muyo! Ryo-Ohki

An average seventeen-year-old named Tenchi Masaki sees his life change forever when he pulls a sword out of a cave and accidentally frees a space pirate named Ryoko who's been sealed away for 700 years. She's not happy about it. What starts as a local folklore situation quickly spirals into something way bigger when an alien princess named Ayeka shows up looking for her missing brother, followed by Mihoshi, a Galaxy Police officer who's somehow both incompetent and dangerous. Before long, Tenchi's quiet rural life is overrun by powerful women from across the galaxy, all crashing at his house, all with their own agendas, and most of them developing an inconvenient interest in him. This 6-episode OVA from 1992 is one of the shows that basically defined the harem genre before it even had a name. But what makes it hold up is the mix — it blends Japanese shrine culture with genuine sci-fi worldbuilding, and the comedy lands without undercutting the action. The character dynamics carry real weight, especially between Ryoko and Ayeka, whose rivalry is both petty and entertaining. If you enjoyed the "ordinary guy surrounded by supernatural women" setup of Ah! My Goddess or the isekai-adjacent chaos of El-Hazard: The Magnificent World, this is the granddaddy. It's also a tight watch at just six episodes, so it never overstays its welcome. A good entry point into classic 90s anime that still feels fun rather than dated.