A light novel series by Konno Oyuki (今野緒雪) and illustrated by Hibiki Reine (ひびき玲音), published by Shueisha Cobalt novels, also known as Maria Watches Over Us elsewhere.
In addition to the novel, there are also drama CDs, manga, three seasons of TV series and an OVA (whose ending theme is, hilariously enough, composed by former Megadeth guitarist Marty Friedman).
