I wholeheartedly second this nomination. This book takes some of the ideas presented in コンビニ人間 and carries them to extremes. I rank it among the best books I’ve ever read.
I will say though “Subject matter can be a bit grim” is an understatement. The book gets very dark and explores topics that could definitely be considered disturbing or triggering. I don’t want to elaborate because I think it’s best to go in knowing as little about this book as possible, but if you find this warning concerning it might be worth looking into some more specifics before deciding if Earthlings is for you.