There are plenty of bird demons in Megami Tensei, and a fair subset of bird girls, but the best bird girl without a doubt is Moh Shuvuu. According to the in-game encyclopedias, Moh Shuvuu is the spirit of a dead maiden from Buryat lore out in Siberia who lures men out into the wilderness, kills them, and eats their brains. Which is quite a bit scarier in my opinion than 99% of the horror I’ve seen or read in my life. Not sure why she’s so upset or bloodthirsty, but my impression is that Moh Shuvuu is more a general type of demon than one specific entity, so maybe they have varying reasons for doing what they do.
Moh Shuvuu is a common recruitable enemy in many Megaten games, usually appearing around the early-mid game. However, she does figure more prominently in a couple of Megaten works, and fanart very often pairs her up in a weird kind of humanXdemon semi-relationship with Raidou Kuzunoha, the 1930s-era demon summoner with his own Megaten spinoff series. All because of one scene in which a Moh Shuvuu begs Raidou to recruit her. The fans can really take something and run with it, can’t they?
Her best role, however, is in Strange Journey as a key character in my favorite series of sidequests in that game. Anthony, one of your crewmates, is a fucking idiot who keeps falling hopelessly in love with attractive female demons in the incredibly dangerous demon-filled Schwarzwelt that’s enveloped Antarctica and threatens to swallow the world. Since the protagonist is canonically really good at talking to and recruiting the demons in that game, he asks you to play go-between with the objects of his desire, but when you talk to them they all mercilessly insult him and say they’re not interested (in fact, a couple of them try to come on to the protagonist, which I can’t help but read as a little confidence-boosting treat for the player.)
Then we come to Moh Shuvuu. Anthony describes her to you and admits that she’s kind of young-looking, but that demons are like hundreds of years old, so it’s no big deal, right? When you find a Moh Shuvuu to deliver Anthony’s message, however, she laughs at him, calls him a “failure of a human” for being into a kid like her, and says she wouldn’t even eat his brains for fear of turning stupid. Now that’s rough. And Anthony really doesn’t take it well when you deliver her response back, making you swear to never speak of it. Poor guy.
But anyway, why would you want to date a girl who’s known for cracking open men’s skulls and consuming their brains? Raidou could probably handle her, being a powerful demon summoner, but that stuff isn’t even canon, and even if it were you’re no Raidou. So I don’t care how cute you think she is, Anthony. It’s just not worth it. Maybe try getting a human girlfriend after you’ve helped save the world, okay?