The Hollow Box and the Maria of Zero) and colloquially referred to as Hakomari (箱マリ), is a Japanese light novel series written by Eiji Mikage, with illustrations by Tetsuo.

[2][a] ASCII Media Works published seven novels from January 2009 to June 2015 under their Dengeki Bunko imprint.

[3][4][5] 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.

[5] Mogi admits she unintentionally created the Rejecting Classroom after being run over in an accident and regretting not being able to convey her feelings to Kazuki, who she had fallen in love with because he saw through her fake cheerful persona.

Both songs were written by Eiji Mikage, sung by En and composed by Kei Fujimiya.