In a lush and verdant land, two sisters hunt for their daily meals, ebon hair streaming behind them as they dash through the forest.

One day, as the elder sister is going about her usual routine, she hears her sister scream. Rushing to the sound, she finds the girl frozen in fear with a beast ready to attack. A single arrow from the woman's bow drives the creature away, causing the younger to spill tears of relief. After embracing the girl, the woman quickly offers up her silver hairpin, a keepsake of their mother her younger sister has long desired. As her tears dry, the girls swears she will be the one to do the protecting next time.

Their hunting complete, the sisters make for home. But when they exit the forest, they see smoke and flame rising in the distance. The woman immediately thinks of the war that is raging in a neighboring nation, and after telling her sister to stay put, makes her way to town.

When she arrives, she finds herself surrounded by the incessant crackle of flames. The town is a slaughterhouse, with corpses on every corner. As she takes in the scene, her younger sister suddenly rushes up to her. She immediately grabs her and attempts to flee, but they are quickly surrounded by enemy soldiers and cut down. As her consciousness fades away, she hears her sister scream, followed by the voice of a soldier uttering two words:

"Sort them."

Thinking that she heard her sister, the woman opens her eyes and finds herself in a prison. Her body is now a stranger — one arm and one leg have been replaced by mechanical substitutes, and her ebon hair has turned white as new-fallen snow.

After breaking out of her cell, she dispatches a guard with ease. He cackles as he dies, gleefully informing her that the captives in this place are all sorted, experimented on, and turned into killing machines. He then tells her that she is one of the failures.

Her mind is filled with a single thought: Is my sister safe? She dashes from the prison, running faster and faster in an attempt to escape the terrible thoughts in her head and feeling in her chest.

When the woman exits the prison, she finds herself in a strange land of flames and blood. As she picks her way through the battlefield, she hears a child's voice and begins to run. Suddenly, the owner of the voice appears before her; it is her sister, twisted and warped as a result of the sorting. The girl makes a sound—a desperate, terrible hiss that might be the woman's name — then chokes on her own blood as a soldier cuts her down like an animal.
After this, her memory goes mercifully blank.

When she comes to, she finds the cold corpse of her sister surrounded by chunks of what used to be enemy soldiers. She gently embraces the girl and closes her eyes. From this day onward, revenge would be her only reason to live.