Fire Emblem: Seisen no Keifu - Hikari wo Tsugu Mono-tachi

Seventeen years after the Battle of Belhalla, the people on the continent of Jugdral suffer under the oppressive rule of the Grannvale Empire.
On the Isaachian frontier, prince Shannan of Isaach has raised a liberation army to fight back against the empire and among its young soldiers was a boy whom the people revered as the "Scion of Light" and the true prince to Grannvale. His name was... Seliph.

Based on the Super Famicom strategy game, Fire Emblem 4: Genealogy of the Holy War. This book exclusively covers the events of the game's 6th chapter.

(Source: MangaDex)