Shakugan no Shana X Eternal song -Harukanaru Uta- is based on the events of the tenth Shana novel. The events in Eternal Song focuses on the events of the Great War, with a certain focus on the lives of two Flame Haze, the previous "Flame-Haired Burning-Eyed Hunter" Mathilde Saint-Omer and "Manipulator of Objects" Wilhelmina Carmel. They were famous as the counterpart of the Crimson Lord duo called as "Pair of Wings" ("Rainbow Wings" Merihim and "Iron-clad Dragon" Illuyanka). Their adventure starts in the middle of the Great War, an event of great turmoil between Crimson Denizens and Flame Haze and a period of great activity between the two factions.
Invaders from the Crimson Realm have descended upon Earth looking for something called the Power of Existence. Whoever possesses this power will control the very fabric of existence. To the rescue comes an otherworldly young girl with fire in her eyes. She may be cute and petite, but she's endowed with enough preternatural strength to save the entire universe. Plus, she's got a really big sword! (Source: VIZ Media)

