When the nation of Grandbell declares war on Shanan's home nation of Isaac, his father sends him into hiding along with his aunt, Ira, in order to protect him should Isaac lose the war. Sometime after leaving Isaac, Shanan and Ira are captured by the barbarians of Verdane and Ira is forced to fight for them in exchange for Shanan's safety. When Sigurd's army invades Verdane in order to rescue Adean, the princess of Jungby, Oifaye and Sigurd discover Shanan in the dungeon of one of the castles in their path. Despite the fact that Shanan is the prince of an enemy nation, Sigurd does not hesitate to take him under his protection, being that he is only a child. When Ira learns that Sigurd has unconditionally taken Shanan under his protection, she agrees to fight for Sigurd while protecting Shanan. Sometime before her disappearance Diadora entrusts the care of her and Sigurd's son Celice to Shanan. Shanan objects, saying that Diadora should take care of her son herself instead of chasing Sigurd onto the battlefield, but he begrudgingly lets her go and is the last to see her before she loses her memories, something he would never forgive himself for, as Sigurd had tasked him with watching his wife.
When Sigurd is accused of being a traitor by his home nation of Grandbell, he gives Oifaye the duty of protecting Shanan and Celice and sends them away into the countryside, telling them to stay hidden until things calm down. Due to this, Shanan is not present when Alvis betrays and executes Sigurd and his army. During the years he and Oifaye spend on the run from the Grandbell empire, Shanan develops into an exceptionally powerful swordsman and shares the duty of leading the rebellion with his best friend. At some point he risks his life to rescue a group of girls being hassled and attacked by the occupation forces in Isaac. Among them is his cousin Lakche, the daughter of his aunt Ira. Lakche develops a crush on her rescuer and grows up admiring and wanting to be with him. Shanan also raises Lakche's twin brother Skasaher on behalf of his aunt.
Shanan carries the blood of the warrior Odo in his veins and is the only one who can use the holy sword Balmung (within the story; through a glitch, it is possible to give other characters the sword), which he goes on a journey to find shortly before Celice is discovered by the occupation forces in Isaac. At the shrine where the Balmung is held he meets the thief Patty who was after the treasures of the shrine herself. Shanan explains that only he can use the holy sword so there's no point in her keeping it anyway and she allows him to take it without a fight. Patty admires Shanan greatly, especially after he saves her from attackers in the Yeid desert. Shortly after they meet up with Celice, Shanan steps down as co-leader of the rebellion to follow Celice's orders, still serving as one of his advisers.
After Yurius is defeated and Celice is installed as the new Emperor of Granbell, Shanan returns home to Isaac to be crowned as it's new king and works to rebuild his homeland.
Shanan has an impersonator from Silesia named Shanam, who serves under Leaf during his rebellion.