Ah yes someone beat me to it! I second the recommendation. The first two books read very much like episodes of an anime. They were released as short stories in a magazine initially, so they're easy on the attention span.

The third book, The Hollow Needle, is more of a novel but maintains the same qualities. After that... bit of a mood shift but you'll just have to see. I understand that it goes back to fun episodes eventually but I'm still recovering from 813, lol.