Its an unusual trend, but, as everything Japanese, why the hell not at this point?
From Inquisitor here:
Photos are popping up of Japanese schoolgirls donning panty masks while doing mundane activities like laundry and performing karaoke. But what started this trend?
The popular theory shared by Kotaku and BuzzFeed is that an odd and eccentric Japanese superhero “Hentai Kamen” has inspired the trend. Billed as “the abnormal superhero” under salutations such as “panty bless you,” Hentai Kamen is a strange “homo-erotic parody of a Power Ranger” who wears panties on his head to conceal his identity and … nothing else.
The photos are likely social-media driven to promote this retarded-sounding movie, which you can see the preview at the link above. Is this what happens to a culture when all the cool superheroes are American?