Long ago, while wandering through a ruined village, Arcelia discovered a child left alone amidst the rubble. She took Guest in as her disciple, and under the guidance of the woman known as the Empire's finest blade and the Silver Sword Saint, Guest gradually grew and became stronger.

Then one day, during a war, the village's defensive line collapsed under the Allied Forces' offensive. The two were ordered to protect the citizens retreating during the evacuation and were deployed together.

While leading and protecting the people through a narrow canyon, they were eventually caught by enemy pursuers, putting hundreds of thousands of lives at risk.

At that moment, Arcelia came up with a plan, but she agonized between her disciple and the people. Ultimately, she chose to abandon Guest.

After giving Guest the order to "draw the enemy's attention," Guest acted as a decoy, leaping into the heart of the enemy army and desperately risking their life to fulfill the command. The reason Guest accepted such an order was because of their strong faith and trust in their master.

After Guest drew the pursuers' attention, Arcelia collapsed the canyon walls, blocking the path and preventing the pursuers from following, thereby saving the people.

However, in the process, Guest, who served as the decoy, had their retreat cut off by the collapsed walls and was eventually captured by the pursuit team.

Afterward, Guest felt a profound sense of betrayal and hatred toward the master and the motherland that abandoned them, joining the Allied Forces of the United Nations. They began to command and lead the army personally as a commander.

Since that day, Arcelia has been plagued by guilt, though she comforts herself by saying it was an unavoidable choice.

Now, four years after that incident, the two encounter each other in the middle of the battlefield.