There was a girl chosen as ‘Hero’. She was the hope and savior of mankind from the destruction of the Demon King. After defeating the Four Demon Lords of the Demon King’s army, she was only one step away from saving the world. However, she was defeated by the Demon King in the final battle. Humanity was once again falling into the abyss. Alan, a boy from a rural village, was a childhood friend of the ‘Hero’. He vowed to take revenge on the Demon King who took away his precious childhood friend. Although he was only an ordinary boy with no special skill, with extraordinary effort, he developed a sword technique that can slay monsters. Finally, he was able to defeat the Demon King, who was already wounded in the battle with the Hero. Revenge could not bring the person back, however, in this midst of grief and loss, Alan lost his life… and found himself reverting back to the time before his childhood friend was taken to the battlefield as the ‘Hero’. Knowing the despairing future, Alan vowed; With this power that I gained for revenge, this time, I will protect my precious childhood friend until the very end.