Unaired 13th episode of Boku wa Tomodachi ga Sukunai.

A retelling of the Arlong Park arc, with new animation.

Rika Furude and her group of friends live in the small mountain village of Hinamizawa; in June 1983, they welcome transfer student Keiichi Maebara into their ranks, making him the only boy in their group. After school, they have fun playing games and spending each day living their lives to the fullest. Despite this seemingly normal routine, Keiichi begins noticing strange behavior from his friends, who seem to be hiding the town's dark secrets from him. Elsewhere, a certain person watches these increasingly unsettling events unfold and remembers all the times that this, and other similar stories, have played out. Using that knowledge, this person decides to fix these broken worlds. However, when certain variables change, the individual is faced with a horrifying realization: they have no idea what to expect or how to stop the impending tragedy. [Written by MAL Rewrite]

Six months have passed since the events in the previous movie. Fate has returned to Uminari City with Lindy as her legal guardian and is living the life of a normal elementary schoolgirl along with Nanoha and her friends. The reunion between the two new-found friends is cut short, however, when they are assaulted by four ancient magic users who identify themselves as the Wolkenritter. As the motives behind the actions of the Wolkenritter become clear, Nanoha and Fate find themselves in a race against time to stop the reactivation of a highly dangerous artifact known as The Book of Darkness. (Source: ANN)