Oh, there is acknowledgement that it needs to be treated alright. Especially by those who suffer it, counterintuitive as it sounds.

It's the basis for the wildly successful and profitable "mental clinic" franchise business. There is one of those ( or two, or three, or four ) in front of every train station in Tokyo. For those who don't know Japan, take a look at a train map of Greater Tokyo and count stations, just for fun. You'll be doing that for a while. Then multiply the number by 2 or 4 to get to the number of "mental clinics".

Those are little more than drug dispensers run by legally authorized pimps with no medical expertise of any kind or a psychiatrist or psychologist anywhere on the premises, but anyone ( and millions do ) can "treat" their anxiety, depression, or insomnia, with half a dozen prescriptions a month. For good measure, they make sure to book appointments weekly in both the clinic near home and also the one near work. And maybe have a third one as backup.

What's needed is proper mental health services, on that you're spot on. And as another comment points out, to erase the stigma of suffering a mentall illness, so people don't use alcohol or these vending machine style clinics with no oversight to treat themselves.

That it is a problem and it needs to be treated everyone's perfectly aware of.

Easy to explain, Japanese deny themselves the right to be weak, they are all supposed to be samurai. Same as in Russia, you are supposed to be a Communist hero whatever happens, mental health issues, especially among men, are as if don't exist there - guys just 'fix' themselves with vodka when they have to, or with suicide if vodka doesn't help anymore. In Russia people can't become hikikomori en masse just because the country is poor so their parents won't be able to feed them - and also because they have same hero mentality so would just beat the crap out of their kids if they tried to lock themselves up in their rooms.

Also, on the good side, in Russia there are much fewer social obligations before people. As in Japan, if you didn't get a college degree to become a salaried employee in a huge company, you are fucked and no one respects you. In Russia, you can do a lot of things and with vast majority population being dirt poor and apathetic, social standards of what constitutes 'successful enough' are very low - some kid who dropped out of college to make $1500 on Upwork writting crappy PHP code at the age of 30 is a success story and his parents are proud of him - in Japan he would be a hikikomori because it would be a total shame to be in that state.

With the added problem of the very strong stigma in japan against mental health issues which means that most would be very unlikely to consult.

I don't have any first hand experience but I have several Japanese friends that got diagnosed with mental illness or depression and given paid months off work by doctor's recommendation, something I'm not aware of in the USA