What does he have in mind?

Zenra school

Josh had always loved all these Japanese videos with schoolgirls going to school in varying exposing outfits and he wanted to recreate this experience.

Women at high school+, both staff and students (and even visitors), must submit to a dress code schedule. On the five days of the week each day has a rule on uniforms: fully dressed, naked, topless, bottomless, underwear only. The days those apply is randomly designated and given to these women through text messages each morning one hour before school.
When wearing the wrong kind of uniform women must remove each extra clothes they put but can't put on anything they should be wearing.
The exception is for the full uniform, going fully dressed in one week always ends with the woman fully naked for the day and only getting back her uniform the next morning.
It is forbidden to change just in front of the school (unless you just got back your uniform) and women have to go to and back from school in their designated uniform.

Josh wondered what would be today's uniform and would discover it when his sister got down for breakfast. (unless she messed things up and put on the wrong one, which would be even better.)

He could hear her footsteps down the stairs.