Japanese anime and whatever, there are samurai with ghost faces. This belongs to Japanese traditional culture or legend, and is represented by ghost fighters.

The ghost face is just something that some soldiers use as a helmet decoration. They hope to be as brave as ghosts in the battle, and at the same time play a role in scaring the enemy. The reason why samurai helmets are made into various strange shapes is also to play a deterrent role, and at the same time to show their identity and avoid being treated as ordinary chess pieces after death.