Whyyyyy. I wanted the girl and blue monster to be ml .....

I think the girl is like the "savior" of those monsters. Based on the future chapters, those creatures were humans that turned into monsters/consumed by their inner demons. The girl somewhat possesses a special ability(?) to turn them back into human when they have sex with her (and she's unaware ig).

SPOILERR!!
She knows that eagle because of the dog tag that the eagle is wearing.