
This it's transleted from the spanish translation and in spanish it doesn't say "my bitch" that would be "mi perra", in spanish it says "mi hembra" that it's closer to "my female". Spanish it's my first lenguage, so unless they check the japanise version and decided this was a better translation, this it's just a case of mistranslation.

The translator already explained that the word used in the original japanese was "mesu" wich is used for female animals and sounds degrading when used for a person. So the spanish is right using "hembra" because it has animal connotations but the word "female" didn't feel right for the translator and decided tha "bitch" was closer to the original meaning. There's a comment from them a couple pages back in the comments
Am I the only one that feels lie to by the cover? He es handsome but I was hopping for the black hairded protagonist xD