So we went from pure yuri dullahan wedding to best girl futa bicorn introduction... the power levels of culture is diverse and leaves the reader throbbing in anticipation.
Never heard of THAT part of Bicorn lore but this is a Japanese author so I'm not surprised by anything they say.
Ironically Bicorn is supposed to have a twin counterpart, Chichevache. The gist is that Bicorns eat good husbands and gets fat because of how easy they are to find, meanwhile his twin eats faithful wives for which she often starves, becoming bony and thin.
I do believe i heard bout that part of Bicorn lore a few times, but all of those times was in manga, but i also never seen a Bicorn being more that "AN EVIL MOUNT!!!" outside of manga.