Otherwise known as Re:Zero kara Hajimeru Isekai Seikatsu, this was an isekai anime that surprised me. I went in totally blind many years ago and remember thinking how light hearted this anime was. It reminded me of the usual video game world anime's I had watched in the past. I was very wrong.
As the story progresses, following our protagonist Subaru on his adventure in this new world after meeting his doom is an upbeat adventure. Yet the unexpected dark tone of this show is a psychological play on its audience. It hits sudden and hard as we realise this world is not what it seems and if you've ever seen Higurashi When They Cry, you'll be in for a treat.
I get frustrated with Subaru at times but after starting season 2, I have once again been dipped into the pool of darkness.
Give Re:Zero a shot!