Ten Years of Sign-In in the Forbidden Zone, Then Back to University as a Doctor

After his parents were murdered, he wandered like a stray dog until he came to a forbidden land. To his surprise, the moment he arrived, the System imprisoned him there and made him perform daily sign-ins for ten years. The five fairy-like sisters guarding the forbidden land also took him in as their apprentice. From then on, he spent ten shamelessly carefree years there with them. After his ten years were up, he had mastered medicine and returned to the martial world!