Ardia, the strongest knight of the Kingdom of Reshfeld and one of the key figures responsible for ending the war between the kingdom and the Vulcan Empire, became a celebrated hero. Despite that, he was executed on false charges.

Carrying the regret of failing to protect Valtrune, the imperial princess who had once saved his life, he is sent back six years in time to the night before the war began.

Determined to change the future and erase his regrets, Ardia swears loyalty to the princess and becomes a knight of the empire.

All to defy fate itself.