I won't say much about this since it is just an ova. But if you liked the humor or gags in the main show, then this ova actually has the best joke in the entire series. I was laughing so hard when I saw it. The joke made all five eps worth it. If ya like humor, watch this and it will provide an amazing joke for you. Though the content overall is still great even without the joke since it is still the slime isekai after all. Also has some of if not the best fanservice in the series if ya like that.