Drag-On Dragoon Story Side is a novelization of the first Drakengard. It seems to follow a branch similar to branch D.
A Union was formed to prevent the Empire’s ambition of reconstructing the world through destruction. The key to preserve order was found in Furiae as the Goddess of the Seal.
The injured Caim, older brother of Furiae, exchanges a pact with a dying red dragon, making them pact-partners. Caim obtains immense power and is overcome by a murderous urge as he swings his blade.
The novelised version of the popular Action RPG expands on the relationships between characters meshed together in the swirl of love and hate.