It's like a few genre trops with different MCs met under one cover. Reverse-isekai comedy (demon prince) + delinquent shounen (also demon prince/blondie) + from-ugly-to-beauty shoujo (well, that girl) + slipping-into-madness seinen (glass boy). Though last one probably won't last, but it would be interesting to see evolving of several interconnected plots, which MCs changing depending on what plot is on the reader's scene rn.