Orphaned as babies, twins Rune and Naoto live at a church on the countryside, raised by a friendly priest named Tako. Shielded from the dangers of the outside world, they live in harmony for many years, until their 18th birthday, when they are suddenly attacked by a group of Royal Soldiers. Fending off the attack, the twins are suddenly informed that the world around them is being consumed in war and darkness, and the only way to guarantee peace for them is to join the Rebellion. But as the pair of siblings fight, they start to learn things about themselves, and each other, that they never knew before.