Himekishi Lilia

Rightful heir to the Leuven kingdom, Lilia Evelvine is a skilled warrior and everything a future ruler should be. Her brother Dirk has other ideas. Consumed by jealousy, he cuts a deal with some genuinely dangerous people: a court enchantress named Kiriko and Sand, a servant of the King of Demons himself. Dirk pulls off a coup, seizes the castle, and suddenly Lilia's inheritance is the least of her problems. The arrangement Dirk made with demonic forces involves extracting the holy energy inside her, and that's where things get very dark, very fast. This is a 6-episode OVA from 2006 adapted from a visual novel, and it leans hard into dark fantasy with horror undertones. The production has a particular atmosphere to it — the soundtrack does a lot of heavy lifting in building genuine dread, and director Hiro Asano gives it a visual style that feels more deliberate than typical entries in this genre. The power dynamics between holy and demonic forces actually have some internal logic to them, which makes the world feel more grounded than you might expect. If you've watched Taimanin Kurenai or Himekishi ga Classmate! and appreciate when a dark fantasy actually commits to its world-building rather than treating the setting as pure backdrop, Lilia scratches a similar itch. It's not comfortable viewing — the tone is consistently grim — but that's clearly the intention from the start.