Manga

I hadn't heard of this one before, but the premise is super interesting. As somebody that reads way too much isekai (see my wall of text in this thread), most of them waste a huge potential of the genre that this one focuses on. Namely, the whole premise of (most) isekai is that there is one or more people that vanish from their world. However, we usually never see anything about the people and places that were left behind. This is one of the reasons why I am of the firm belief that most isekai are just fantasy stories that have the unneeded addition of the reincarnation/summoning/whatever isekai element added to them.