The former strongest assassin named Beruto, retired from the hero's party after becoming unable to fight effectively because of certain injuries he sustained when they drove back the demon king. So he opened a pharmacy in his hometown.

One day, a girl named Meiru who possessed the power of a holy maiden, paid him a visit. She confirmed that Beruto's injuries were in fact, a hex from the demon king. With her power, the hex on him becomes weakened and he regains one part of his abilities, so he finds himself returning to a life of adventuring as her bodyguard.

With his sealed powers unleashed, Beruto will once again become unmatched!!