Utsuro no Hako to Zero no Maria

The Empty Box and the Zeroth Maria, known in Japan as Utsuro no Hako to Zero no Maria (空ろの箱と零のマリア, lit. "The Hollow Box and the Maria of Zero") and colloquially referred to as Hakomari (箱マリ), is a light novel series written by Eiji Mikage (ja), with illustrations by Tetsuo. ASCII Media Works published seven novels from January 2009 to June 2015 under their Dengeki Bunko imprint. The novels have been licensed for release in North America by Yen Press.

Plot
The story revolves around a carefree boy named Kazuki Hoshino, who is intensely attached to his normal daily life, and Aya Otonashi, who suddenly transfers into his class for the 13,118th time and declares her goal to "break" him forthwith. This starts an avalanche of events, involving a supernatural device known as the Boxes and a supernatural being, which pits the two characters against each other causing their friends to be caught under their crossfire.