https://youtu.be/cXC6rasajmo?feature=shared

>>49651783
It's never really made sense. It turns off and on for no reason, plus Bernkastel has pretty empty eyes, emphasizing her mystery and over some demon or mystic nature.

I think the gacha actually takes the eyes and uses them to symbolize a specific kind of "outbreak" syndrome which everyone can get. If I'm remembering right.