The protagonist, Roush, spent every day happily with his beautiful childhood friend. One day at the age of fifteen, he attended the ceremony called the “judgement”. There, Roush was bestowed a useless skill “Unimportant” while his childhood friend was bestowed the legendary skill “Sword Princess”. The hero caught wind of that and pulled in Roush’s childhood friend as his companion in the subjugation of the demon king. Roush was going to become separated from her, but they made an engagement promise at the time. He was earnestly waiting for his childhood friend to come home. And so, at last, his childhood friend had returned. Roush was overjoyed as he welcomed her home. However, it was already too late; she had already given her body and her mind to the hero… In despair, Roush vowed to have his revenge.