Okay, so, high schools in Japan get a single month of summer vacation (basically the entire month of August). They also tend to get a couple weeks around the new year and several weeks between school years (aka most of March). I don't know a detailed enough breakdown of holidays, school events, and school day length to compare total hours of instruction, though.
Japanese and American university systems are commonly contrasted; Japanese universities are absurdly difficult to get into, but once you get in, it is very easy to graduate, while American universities are fairly simple to get into but require a lot of work to graduate.
Japan's education system is consistently ranked near the top, while America's as of late tends to be fairly middle-ground (I recall it being around 30th).
I cannot speak for how stressed the students tend to be, because I haven't kept up-to-date in that area. I know it used to be a huge issue, but Japan has been starting to open up toward mental health issues in general over the past several years, so I don't know how much of an issue it is these days.
