Summary

In an alternate future... the government of Japan introduces the Media Betterment Act (MBA) at the dawn of the Seika era. The MBA allows the government to censor and/or confiscate any publication that it deems unsuitable for the public, using force when deemed necessary.

To counteract the MBA, opposition legislators within the Japanese government pass another law, the Library Liberty Act (LLA). This Act allows libraries to defend the freedom of information, and thus become the sole opponent to the MBA. Under the LLA, the Library Defense Force is created. Over the years, conflict between the opposing forces escalates.

30 years after the enactment of the MBA and the LLA, Kasahara Iku joins the Kanto Library Defense Force to protect books, just like the Library Defense Force member who saved her when she was in high school...