"Rebirth", "Single Heroine" and "No System" Memories always punish those who miss the past. An orphan was adopted and raised by his master since he was a child. However, after his master passed away, he failed to protect his master's daughter - the junior sister who grew up with him.
In order to make up for his regrets, he traveled around for the rest of his life, searching through ancient books just to find a chance to go back to the past. Finally, when he was dying, he finally got his wish and returned to the past...
