One day, the protagonist, who worked at a so-called “black company” doing simple tasks of typing text from early morning to late at night, died of exhaustion due to lack of sleep. He overworked himself and deprived himself of sleep. Then, he found himself back 20 years ago, when he was six years old. A familiar house, his youthful parents, and his youthful body. In the midst of the nostalgic scenery, he saw something that looked like a status window you see in every game. It showed his status, level, and skills. “I’ve got skills! What? What are ‘Muscle Strengthening’ and ‘Magic Strengthening’?” “The more I train, the more it shows up in the numbers, it’s so fun!” “If I keep training like this, before I know it, I’ll become too strong.” A High School student. The dungeons have appeared as if they were made for each other. He was also wearing armor and he appeared as the main character.