I did it to illustrate my specie Niyassur (ニヤスル - Niyasuru).

Sorry the errors, I used the translator to write it. :[

The Niyas have the tradition of wearing masks that each one does individually when they reach the age of 15. They paint them using ink of their own tail, the mask reflects a lot on the personality of each one. Some Clans use specific symbols in their masks to mark their members or to define a hierarchy within their clan.
Most of the time males do not wear their masks, since females use them more often because of their powers that surround their sight.

When they are with others of their species (among members of Clan, War and Events) the Niyas use them to avoid direct visual contact with others. It is considered a complete offense and disrespect to touch the mask of another Niya, prolonged direct visual contact can also cause many problems (and ugly quarrels) among males.