naked school attendance
A subset of zenra fetish involving a classroom of students who is either not wearing certain clothing items (being topless, bottomless, etc.), a revealing school uniform, or simply being nude, with them being either oblivious to their state of undress or treats it as a normal activity.
Typically, the setting treats these impractical "uniform" or nudity as their "school uniform", while some other instead use the "nudity day", a supposed special school day where all students and teachers must attend the school naked.
This is not limited to classroom, as it also covers when such naked students travelling to school, often within the presence of other people who are otherwise wearing normal clothes.