Anime Like Darkness of the Sea, Shadow of the Moon
A cave full of corpses kills everyone on a track team except two sisters, and the horror doesn't end there, it's what happens between them after that the show is actually about. Lumi's jealousy over a boy becomes radioactive when they're the only survivors, when one of them might be something other than human, when trust becomes a weapon. The twin dynamic does what it promises: betrayal, psychic connection, and the specific dread of being trapped with someone who shares your face but not your loyalty.
SYNOPSIS
Twin sisters Lumi and Luka share everything: their faces, their school, their feelings for the same boy. When Katsuyuki chooses Luka, the rejection cuts deeper than a typical love triangle. Lumi's hurt transforms into something darker, a resentment that festers beneath forced smiles. On the way to a graduation party, the twins seek shelter in a seaside cave. What should be a brief refuge becomes a tomb. A sickening stench fills the air, and bodies begin to reveal themselves in the shadows. One by one, the group succumbs to an inexplicable force. Only Lumi and Luka escape. But escape isn't freedom. Something shifts in Lumi after that night. The girl who stumbles back into life isn't quite the same person who entered the cave. When she begins appearing in impossible places, materializing from walls and floors in her sister's room, Luka realizes the horror isn't behind them. It's living in her home, wearing her sister's face, and it wants something only Luka can give.
