One of the cultural differences that interests me is the wearing of tights by boys in some countries; it would be very rare to see a boy in tights in Britain. In Japan their use as acceptable wear seems to be more frequent.
There are rules, though! Boys wanting to wear tights when playing football have to observe the rule that the tights, short exercise lycra shorts or inner wear has to be the same colour as the main uniform. In case of doubt, there are helpful illustrations, shown below.
NG here is the ‘not okay’ message. These rules apply for official matches and things are more relaxed for practice sessions.