Im attending university in japan and it is the same here. Although we dont wear a uniform, it is true that you will not see short sleeves until a certain date. For winter is even worse I think. It was freaking cold here and everybody was still in their autumn clothes. Personally, I could not take it and I was the only one wearing thick layers for a while.
As for school prices, university is very expensive. Public (national) ones cost more than 500,000 a year. I will not even say for the private ones, as they vary a lot, but I have seen it go as far as 4 million for medicine school. I do not know how is it elsewhere, but it is extremely expensive under mexican standards. Back there for the money of a national public university I could pay half a year in the most expensive private college; or 50 years in the mexican national university
On the same topic, I have seen a quite disturbing sight. While I was attending a homestay program, I got to talk with some high school japanese boys and girls. They were divided into three classes per year. From A to C, apparently, C being the most advanced. I asked them how did they get to be in C class, and they replied they have been like that since junior high, or even before that. The problem is that depending on the class they were, they could only apply to some universities. So it seems that the whole education future of these children ewas pretty much decided as soon as they entered junior high. It is kind of frustrating.