, often shortened to , is a Japanese light novel series written by Oyuki Konno with illustrations by Reine Hibiki. Originally written as a short story in 1997, Shueisha published 39 light novel volumes from April 1998 to April 2012. The story focuses on a group of teenage girls attending the Catholic Lillian Girls' Academy in Tokyo, Japan. Its storyline largely revolves around the lives and close relationships of the school's student council known as the Yamayuri Council.