I am Satoru’s one and only cat. And Satoru is my one and only pal. And a proud cat like me wasn’t about to abandon his pal. If living as a stray was what it took to be Satoru’s cat to the very end, then bring it on. [loc. 2825]
Nana (not his choice of name) is a streetwise stray cat who, after being hit by a car, is taken in and cared for by a man named Satoru. They live together happily for five years, but then Satoru takes Nana on a series of road trips to visit old friends who he hopes will give Nana a home: 'Something came up, and we can’t live together any more'. None of the friends -- whose backstories are told in third person -- are able to offer a suitable home, and eventually Satoru and Nana end up living with Satoru's aunt Noriko, who is not a cat person. At least not to start with.
This could have been a cloyingly sentimental book, but Nana's sassy street-cat voice elevates it. It's a story about loss and grief as well as about the love between a man and his 'darling cat'. It brought tears to my eyes at several points (the ending is sad but hopeful). I also found it immensely humane and comforting.
While I was reading, I was mostly interested in Nana: after I'd finished, I went back to look at how Satoru's past -- revealed as he meets each set of friends -- affected Satoru as he grew to adulthood. There is loss and grief, but Satoru weathers those episodes with grace. He doesn't seem to have had romantic relationships (or possibly Nana just didn't notice or care about them) but he is full of love for life, and for his friends and family. And for his darling cat.