Tasuku Nakamura, who was thrown into the sea in a marine accident and tried to help his best friend, ended his short life of 25 years. Formerly a mediocre office worker, when he opened his eyes, he was in the form of a six-year-old baron's daughter, Sophie Linier. At first she was confused by the changes, but she was reincarnated as a beautiful girl and decided to live as a lady in a different world. The struggle of a 6-year-old girl with the soul of a 25-year-old boy begins ... !! Note: The following chapters were split into two parts in the original serialization and later combined in the volume releases: 1, 3 to 5, 7 to 15, 18 to 23, 25, and 27 to 32.