A Regressors tale

our main character shin is a 32 year old character who is living alone without any family or a gf or wife he works as a cooperate slave working as a designer where none of his work gets recognized and he is tired of his life but one day after he goes to sleep he wakes and sees that he is back in his body when he was just 15years old this is the story of shin after all that happened in his life and how he changed his grimm future