Fire Emblem if: Nibelung no Houkan (Crown of Nibelung) is a manga whose plot-line focuses mainly on Leo, the second royal prince of Nohr. It is an adaptation of the game and follows the Revelation route. The Avatar is depicted in her female incarnation. It makes some references to other material related to Fire Emblem Fates, such as the drama CD. For example, it mentions the Clarkenstein villa within the imperial palace, where the Nohrian Royal Family officially resides.

In 19th Century England during the Victorian Era, there is the Kingdom of Tarnina Ulaniborg. The Kingdom has a Royal Academy where Royalty and Commoners can study Astronomical Research in hopes of becoming a Royal Astronomer. Astel Paschalis attends the Royal Academy as a scholarship student with a certain hidden motive.

Once, there was a hero who vanquished the darkness on this land and liberated the people from it. Then he built a kingdom, and had his descendants to rule as kings. Although they had ruled the land for so many years, the truth is the politics is being centered on the elders from each region of the kingdom. A prince's journey is about to begin.

Leto is employed as an apprentice by the skilled mercenary Alpha, from the mercenary unit Boreas. He struggles to rid himself of his apprentice status and be accepted by Alpha. However, as a mercenary, many painful encounters and terrible experiences await him…

A collection of side stories for +C: Sword and Cornett.