Forehead Protector

This character wears Japanese armor Hachigane.

The term "Hachigane" refers to a piece of armor that covers the front half of the head, omitting the back half of the helmet bowl (Hachi). It is made by joining several iron plates with a metal fitting called "Tetsu Byou" and leather, or by stretching a single iron plate. Headband variation commonly seen worn by fictional anime/manga ninja character.

Variation and example