I wonder if they just like to make kids clean pools in Japan (or at least that's what anime would have you believe). I don't think that I've ever even seen a drained pool, let alone one being cleaned.

It's usually done by robot because draining takes a long time and they have to do all sorts of test on the water that goes back in instead of the routine test and tweak.
An outdoor pool might get a drain and clean once a year I suppose, but generally you don't need to scrub a pool because the salt or chlorine kills anything that would need scrubbed off (like its supposed to).

I remember I had the day of cleaning pool once a year at junior and middle school.

midzki said:
I remember I had the day of cleaning pool once a year at junior and middle school.

Yes. Sadly those days are behind us now. ; ) No more water wars or messing around with those perverted boys and their fantasies.