The manga proposes to follow Ewalt, Sieg and Laurent in their adventures at the Academy of the Sacred Knights.

It is said that the Emperor once opposed the dreadful "Lights" to protect his people from the Great Fire that ravaged the ancient capital. During the long battle that followed between Sacred Knights and Magicians, the Gilbert family distinguished themselves by defeating their leader, the "Pure Blood Sorcerer", and thus brought peace to the Empire.

As a reward for his service, Ewalt's uncle Colin Gilbert was promoted to the rank of commander of the Sacred Knights unit and received a gift from the royal family.

While history tells us that the One Grimoire, the source of the sorcerers' powers, was burned to the ground in exchange for their lives, Ewalt always suspected that the treasure so preciously kept in the storeroom of the Gilberts' main residence was none other than this terrible artifact. So when a book resembling the One Grimoire suddenly appears in the black market, Ewalt goes looking for answers to preserve his family's honor. (Source: Mangaupdates)

Adapted from the mobile game Magatsu Wahrheit (KLabGames).

There is an anime part two : https://www.anime-planet.com/anime/magatsu-wahrheit

Here tracking link : https://www.mangaupdates.com/series/zswq051/magatsu-wahrheit-hitotsu-kiri-no-madousho