A boy who lost his parents at a young age was taken in by a wandering swordswoman and raised to be her apprentice. Years later, she dies during a fight with the demon lord. Now, 18 years old, the boy moves in with his mentor's ex-lover who is grieving over the loss of the love her life. While taking care of this witch-lady, he vows to learn magic under her, so he can grow powerful enough to defeat the demon lord.