It could be that his past holds something that could put him at a disadvantage or make him vulnerable. Or perhaps it's a part of his character development and will be revealed later for a dramatic twist.
The player might hide his past because it could affect his current relationships or status in the story. Maybe it's related to a mistake he made and he's afraid of being judged.
Maybe he is ashamed of it. Some past works might not be up to his current standards, or perhaps there are elements in the novel that he doesn't want to be associated with anymore.
It could be that revealing his past would put him or someone else in danger. Or perhaps it's just too embarrassing for him to share.
The player might change his identity or keep silent about his past. Simple as that.
Maybe he uses disguises or changes his identity to hide it.
The player might hide his past because he's ashamed of it or because it's tied to something that could prevent him from achieving his goals in the story.
The player might change the title and his name associated with the novel so that it becomes difficult to trace back to him. He could also use some legal means like copyright restrictions to limit its availability if possible.
Maybe he's afraid of being judged or has something to protect.
Well, 'Mystic Warrior' could be comparable. Both have elements of hidden pasts and unfolding mysteries. It has a similar tone and story progression.
It depends on which manga you're referring to. Different mangas have different storylines and character fates. You could provide more details for a more accurate answer.