Cambrian

When a scientist with nothing left to lose decides to experiment on himself, it goes about as badly as you'd expect — except much, much weirder. Dr. Yamagishi got kicked out of the academic world for messing with human cloning, so naturally he moves on to something even more ambitious: engineering a new human species he calls 'Cambrian.' He injects himself with whatever he cooked up, and instead of a breakthrough, he transforms into a mass of grotesque, writhing flesh armed with tentacles. The experiment worked, just not in any way he intended. This is a 2-episode OVA from 2005, so it's short and wastes no time getting into the horror of what Yamagishi has become. The sci-fi framing — rogue scientist, forbidden research, evolutionary tampering — gives it a slightly more grounded setup than pure fantasy tentacle fare, which makes the body horror land a bit harder. There's a real Cronenberg-esque 'body as consequence' thread running through it, where the transformation feels like punishment for hubris rather than just shock value. If you've seen Demon Beast Invasion or Bible Black and want something with a similar dark, unsettling tone wrapped in science fiction dressing, this fits that same neighborhood. La Blue Girl fans will also recognize the aesthetic DNA. It's not a feel-good watch by any stretch — the vibe is consistently grim and uncomfortable — but if grotesque body horror mixed with mad scientist territory sounds like your thing, Cambrian delivers exactly what it advertises in a compact runtime.