I was on a two-year exchange program to ICU in Tokyo, Japan. This is a short description for those considering taking part in such a program.
The abbreviation ICU officially expands to "International Christian University", but internally we often used "Isolated Crazy Utopia". Isolated utopia because it is basically a huge park removed from the busiest parts of Tokyo with some university buildings in the middle. Maybe not crazy, but it does feel a bit strange to have such a huge space for just a few students when the rest of Tokyo tends to be quite crowded. For example the campus has a tea house maintained by the students and a long boulevard of 106 cherry trees leading from the front gate to the chapel.
For the exchange program there were two choices. Either you could take it easy and just take a few Japanese lessons each week and balance it out with other topics, or just go fully crazy and only study Japanese all the time. I chose the full insanity nightmare mode which consisted of six hours of Japanese lessons every day, with homework and a daily quiz you additionally had to prepare for.
I was improving at light speed. Each morning started with a kanji quiz for which you had to prepare for the previous night. This helped keep the pace, providing some nice continuity from the previous night to the start of the next day. The classes were about reading, writing, listening comprehension and speaking. Personally I found the reading classes to be the most helpful ones. We had assigned reading which used some of the same characters as we had learned for the morning quiz. The class would take turns reading each line of the text, so there was pressure on not to mess up your part.
In writing we spent time practicing the writing of kanji characters, sometimes discussing their meaning. There was no particular system besides repetition. At the time I felt like having no system was a great waste of time, as I was a believer in the Heisig system at that time. I've changed my mind a bit since then, but still feel that it might have been beneficial to split the kanji characters into parts (radicals) and spend time studying the radicals, instead of just rote repeating the whole characters. Some writing was creative writing, where we would compose short essays in Japanese ourselves. That was my favorite part, as coming up with stories can be great fun.
In listening comprehension we watched videotapes of news programs and some shows custom made for Japanese learners. The speaking was most fun for me. We just had a general topic in the classroom and could freely talk about that topic among classmates during the class, as long as it was in Japanese. The teacher was listening in on our conversation and would jump in to correct any mistakes.
For improving your Japanese, doing an exchange program in Japan is certainly more effective than studying only a few lessons a week in your home university outside Japan. The most important thing in learning seems to be immersion, having a lot of chances or even being forced to constantly use the language you want to learn. It might be frustrating at times, you will get exhausted, but you will learn.