At 2nd anniversary colored page, everyone's choice election, Isekai category, won 1st place... The series is not Isekai....or Isekai actual mean is castle era story or something, not reincarnation thing. Now I'm confuse. Lol
The way japan defines Isekai is just 'a different world' so any story that doesn't take place on Earth and is instead a made-up world is an Isekai. It's just that in English parlance we use it as blanket term for all the sub-categories about people being reincarnated in another world/summoned to another world/transported to another world/etc.