We were lucky to have a guest from Japan visiting with a child in Reception, they were doing triple digit multiplication and long division already at that age.
???
I live in Japan, speak and write Japanese fluently and have a child in public school here (as do most of my girlfriends--I know the curriculum here inside-out). This is absolute errant nonsense, sorry.
For a start, compulsory education does not officially start till age 6 yearthe equivalent of Y2 in the UK. Reception-aged children are in kindergarten here. Japan does not have an officially mandated kindergarten curriculum-the kindergartens and daycares here run the full range, from "forest school/100% free play in the mud," to very academically focused kindergartens (however, even these ones are not teaching long division to 4yos as standard, seriously. And I do know what I am talking about because I have known one or two people who have used them).
The majority of kindergartens and daycares do some academic work but at a similar level to the average reception class-if that. A lot of parents do do work with their kids at home during the 3-6 age range or use Kumon etc, but again it depends on the parent and the area. When the kids start public school at age 6, the curriculum literally starts from zero in terms of literacy and maths. Of course, you will get some private schools that are more pushy, but these are not for the majority of kids and again, they are not expecting that kids will have been doing long division at 4yo eitherI know this, because I've seen the past-paper collections in the bookstore.
The Japanese public school curriculum moves at a similar pace to the average English school in the early elementary school years. The main difference is that everything is more "solid" and there is a lot more emphasis on really, really practicing stuff and getting very fluent and quick (they get send home with a lot of summer homework and there is targeted maths practice homework every single day during term time). The kids therefore tend to be in a position to make faster progress with maths as they approach secondary school age. I don't like everything about Japanese schools but I think maths for the most part is well taught.
My kid is in second grade (age wise, that is like Y3 in the UK). They are doing double-digit adds and subtractions and starting multiplication tables. That actually sounds a little late to start by UK standards--on the other hand, they make them practice and chant them like hell, so the kids really really do learn them and are expected to be fluent by the end of the year.
Kids who are tutored outside school (which becomes common in urban areas from the equivalent of Year 4 onwards) will definitely make faster progress than the standard curriculum. But then, you will also come across a big range in attainment levels in English schools too, especially (again) in big cities where tutoring is common.
I don't know what on earth this "visitor from Japan" was trying to tell the previous poster, but this is not representative of the Japanese school system. Maybe they had some kid who is a maths genius and is also being juku-d to death, who knows.
Bear in mind that Japanese people overseas often see themselves as ambassadors for their country and give a "PR" version of what goes on their country for foreigners, depending on what they think the person wants to hear or depending on what impression of Japan they are eager to create (which is why you get people giving either ridiculously accelerated ideas of educational attainment for the kids back in Japan, OR insisting that Japanese kids do zero academic work before age 6--my experience is that neither of these things are actually true).