Happy Lesson! It has the tag of a harem, but honestly I didn't see as many typical harem aspects in the show as I thought I would. The premise of having all your kawaii teachers [and a loli one too] come live with you sounds like the perfect setup for some intense ecchi scenes, but what I actually found was a little different. The only ecchi thing I can even really remember is probably that tomboy teacher always pushing the main character into her tits. Besides that it was more like a comedy and I think it was genuinely funny. Besides one over dramatic and pretty muchgarbage episode with some random girl and I think the main character had to like appreciate his "mamas" or something, every other episode started with that amazing intro and was really funny. If your looking for a show that basically encapsulates that 2000s anime aesthetic and is really short, so short that you could watch it and probably finish it in two class periods, then maybe give this show a watch.