It could be a new character created specifically for this fanfiction. Maybe a powerful wizard who has been in hiding and uses the mask to conceal his true appearance while he moves around Hogwarts or the wizarding world.
It might be related to a secret society or a dark magic object. In the Harry Potter universe, there are often mysterious items with special powers. The hollow mask could be one such item, perhaps used for disguises or to access hidden places.
The Shindo Life story involves a world filled with ninjas and various elemental powers. Players embark on a journey to become powerful ninjas, facing challenges like battles against other players or powerful in - game bosses. They can train, upgrade their skills and unlock new abilities as they progress through the story.
In Shindo Life story, the main character is of course the player's avatar, a ninja. But there are also important NPCs. For example, the village elders play a crucial role. They are the ones who often give out important quests and advice. And then there are the rival ninjas from other clans. They can be considered main characters in a sense as they drive the story forward through their actions and interactions with the player's ninja.
To get story mode in Shindo Life, check the game's main menu or quest log. Sometimes, you need to unlock it by achieving certain in-game milestones or interacting with specific NPCs.