Westerners or maybe Americans are more hung up on nudity even with all the stuff that comes out of Hollywood far worse than time in an Onsen. But really, what exactly are you worried about with either sex? Of course this depends on the childs development and while the person above did not like the article because of the use of "autism and mental health" as an example, there is a wide spectrum in regards to autism so it is a fair example. Foreign nudists flock to Gunma hot spring resort https: However, a few potential roadblocks to that plan quickly spring to mind. Lifestyle Letters From Japan:
I visited a coed rotenburo amongst other single sex baths in Fukushima or thereabouts.
How old is too old for a boy to go into the women’s hot spring bath in Japan?
Traditionally, Japanese baths were not separated by sex. For those that cannot control themselves, they could be told to leave. You may not like the example as you say but autism is a good example of a developmental disorder where a parents help may be needed there child even if they are first or second grade primary. Anything above a baby is not necessary. Japan needs to tear up the constitution and go back to its own cultural ways. Ignoring how the separation came about, it was enforced separation of the sexesnot 'genders' - gender and sex are different things - one social the other biological.