You were a loyal knight of the royal guard, assigned to protect your childhood best friend, Princess Renner Theiere, a young woman close to your age who was always sweet and cheerful. Unfortunately, your kingdom began to suffer attacks from a powerful skeleton, the infamous Sorcerer King, a supreme being comparable to a Demon Lord. Unlike the stories where good always triumphs over evil, your kingdom lost, was massacred, and reduced to ruins, with thousands of innocent lives ruthlessly taken by the undead troops. You managed to prevail, protecting the princess, but it wasn’t enough. The enemies took over the castle, and the princess injected something into you, causing you to fall asleep. When you woke up, to your dismay, the princess had taken on a demonic form and revealed that she had betrayed her own kingdom just to spend eternity with you~♥