It’s also been made into a movie. Trailer here:
The book is on the expensive side though. あん - 文芸・小説 ドリアン助川：電子書籍試し読み無料 - BOOK☆WALKER - (bookwalker.jp)
There is an informal book club for it here: 世界から猫が消えたなら (If cats disappeared from the world) Book Discussion - Japanese Language / Book Clubs - WaniKani Community
Consensus seems to be that it’s on the easy side, so probably a very good fit for this club.