Fire Emblem: Heroes of Light and Shadow (Nintendo Cinematic Universe)

Fire Emblem: Heroes of Light and Shadow is a Japanese graphic novel.

Summary
After defeating the sorcerer Gharnef and the Dark Dragon Medeus, peace is restored to Archanea and Marth restores his kingdom. His ally Hardin ascends to the throne of Archanea, but begins hostile military expansion across the continent, forcing Marth to confront his old friend and the force driving him.

Plot Elements

 * Hardin begins the forceful military occupation of neighboring countries, with Marth's army being used as part of the conquests.
 * When Marth grows suspicious of his role in Hardin's plans, he is branded as a traitor to Archanea and is relentlessly hunted down by Hardin's forces.
 * Receiving the Fire Emblem from Nyna by way of a courier, Marth and his army escapes to the desert of Khadein and meets with Gotoh. He explains that Hardin has become possessed by the evil power of the Darksphere, which Gharnef secretly gave to him, and that only the Lightsphere can counter its power and save Hardin. Marth is also tasked with locating three other magical spheres in his quest: the Lifesphere, the Geosphere, and the Starsphere (the latter of which must be reassembled through the collection of Starshards).
 * Marth and his allies journey through the icy mountains to obtain the Lightsphere, then stage a final assault on Archanea to liberate the continent from Hardin's madness. Though the Lightsphere nullifies the Darksphere's power, Hardin is critically wounded in his battle and can only apologize to Marth for his actions before he dies.
 * Marth inserts all five into the Fire Emblem and unlocks its full power as the Binding Shield.
 * Gotoh then arrives to inform Marth that Gharnef has kidnapped several female clerics, including Princess Nyna and his own sister Elice, to serve as sacrifices for the revival of Medeus.
 * Marth leads his army to an ancient temple where Gharnef holds the ceremony.
 * After killing Gharnef, retrieving Falchion, and rescuing the clerics, Marth confronts Medeus, who has taken the form of an enormous dark dragon.
 * Using the Falchion and Binding Shield, Marth slays Medeus.
 * With peace restored to the land, Marth and Caeda, now married, become the rulers of all Archanea.