Yamata no Orochi is a boss in Monster Girl Quest: Paradox.
Monsterpedia Entry
Attacks
Strategy
Evaluation
"Not only did you not get rid of her, but you ended up as the sacrifice... Are you sure you didn't go into that trying to be the sacrifice? Yamata no Orochi is a very powerful enemy. Her strong physical and Pleasure attacks on top of a strong Fire attack make her quite a threat. She's resistant to fire and has no particular weakness. Status ailments barely seem to work on her aside from Blind and Sleep. It is advisable to Blind her and attack her while she's asleep. Even so, the battle will be difficult. If you're not properly leveled you may not be able to defeat her. If that's the case, train more then come back and challenge her again. "