Siegrune & Brynhild were chosen for the next generation of Gun Bullet Children. They were both created by being fused with angels, almost to the point of death. The two have overwhelming powers, but the price for that is that their hearts and minds have become twisted.
Together, they are capable of summoning the most powerful of all magical beasts, Fenris Wolf, to possess them. They can also tap into Fenris Wolf's boundless magical abilities. This ability was originally Siegrune's ability alone, but the Church brought it under control by transfusing half of that power into Brynhild when it proved too difficult for Siegrune to control alone.
Fenris Wolf, which Siegrune can transform into, is a monstrous creature that has both polarities, but his power is considered dangerous, which explains why the dark attribute was transferred to Brynhild as a safety. After Brynhild dies in the final stage, Siegrune absorbs her body to become the final boss, Fenris Wolf.
- Both Siegrune and Brynhild were named after Valkyries of the same name.