About a year or two ago, someone recommended a phenomenal dystopian novel about people who don’t have kids and are sent to live in a luxury facility where they serve a particular function for their remaining lives. It was by a Japanese author, I believe a woman. Does anyone know the name of the book and/or the author?

Bonus question: Any other Japanese sci-fi/dystopian/magical realism book recommendations?

I have dug around the net for a little while now, and other than direct purchase from Japan I am having trouble finding light novels. Specifically for several anime series I liked and want to read the originals for. Anyone know where I can find light novels in general for purchase or otherwise?