Ichinomiya Shingo, a young 25 years old, single, company worker, while thinking of tomorrow’s busy working day goes to sleep. However the moment he woke up, it was a room unknown to him.
He then learned that he was inside a 6 years-old boy and had taken over his mind.
Furthermore he learned a lot from the memories of said boy: he was born as the youngest child (8th son and 10th child) of a poor noble family living in the back country. Having no administrative skill, he couldn’t do anything to manage the vast land his family has.