Kashin Koji's mask from manga Boruto.

You can add subdivision to the low poly model to make it looks better.You might need to use some deformers or sculp tool to make the model fit your characters.
Also, you can easily rig the mask to you characters head.

There are some model details:

• Models with UV unwraped.
• No texture map included.
• Model in obj and Stl format.