I haven't watched a lot of isekai and reverse isekai genre, but there's this anime that I really enjoyed back then and I'm more than excited to watch again. It's called BLOOD LAD. The main character is a very powerful vampire who ruled the demon world, but he is such a huge gap character (which I love a lot!). Despite being the most powerful, he is such an otaku that when the chance was laid for him to come to earth, he was more than ready to do so! I should really re-watch this soon!