Shadow

Without a war to give her purpose, Karyu is a ninja adrift. The Edo period brought peace to Japan, which sounds nice until you realize it left highly trained killers scrambling for freelance work. She ends up doing hired assassinations just to stay relevant, and the OVA kicks off with her taking a contract on a merchant, straightforward enough, until she gets there and discovers the merchant's servant is also a ninja, and not a slouch about it either. Her name is Uzume, and the two of them are pretty evenly matched, which turns what should have been a clean job into something much messier and more personal. That rivalry is really the core of it. Two skilled women, both operating in the margins of a society that no longer has much use for them, deciding their conflict through increasingly brutal means. If you liked Ninja Scroll or Basilisk: Kouga Ninpou Chou and want something that leans into that same bloody, historical ninja aesthetic, Kage scratches that itch. It's a four-episode OVA from 2004, so it's compact and doesn't overstay its welcome. The action is graphic and doesn't pull punches, and the historical backdrop of ninjas becoming obsolete gives it a bit more texture than a straight-up fight romp. Worth noting upfront: this is adult content, so go in knowing that. If you're okay with that and enjoy dark, visceral action with strong female leads, it's worth the short runtime.