Iku (Nana Eikura) joined the Library Defense Force after a member from that team retrieved an important book that was targeted for censorship. She is assigned to work under Atsushi’s (Junichi Okada) team. She endures Atsushi's harsh treatment and looks for the member who retrieved her book. She also finds herself becoming attracted to Atsushi. Iku meets female high school student Marie (Tao Tsuchiya) at the library. Maries has a hearing disability. She is also a childhood friend of Mikihisa (Kei Tanaka). Iku senses Marie’s strong feelings for Mikihisa. Asako (Chiaki Kuriyama) works as a clerk for the Library Task Force. She has frequent meetings with curator Shuji (Aoi Nakamura). This creates complicated feelings for Hikaru (Sota Fukushi). One day, Mikihisa is arrested because of a book he recommended to Marie. Official reason given is because the book is unsuitable for disabled people. The members of the Library Task Force are angered by Mikihisa's arrest.

In a dystopian society where the government controls all media, a military force is formed to protect books from censorship. The protagonist, a young woman named Iku Kasahara, joins the force and battles against corruption and oppression to preserve freedom of expression.

Set 18 months after movie "Library Wars." After the government's enactment of the Media Betterment Act, battles wage between the Betterment Squads and the Library Defense. The Library Defense resists censorship and advocates freedom of expression. The biggest battle awaits for the Library Defense.