There are more than 100,000 international students enrolled in Japanese universities, professional schools and junior colleges. A standard examination is used by nearly all national, roughly two thirds public and half of the private institutions as the basis of admission. Remaining institutions use their own exams. Most of the teaching is conducted in the Japanese language, but there some universities that offer programs in English.
Japanese language schools are a common site in cities across Japan. They offer a variety of courses of different durations and levels of language proficiencies. Many foreign students enrol in such schools and take preparatory courses before moving to a university for formal studies. Summer courses in these schools allow foreigners to learn Japanese and become familiar with the country’s culture. There is classroom instruction during the day and a variety of activities planned in the evenings by the staff. This form of study allows one to learn and yet enjoy themselves. Short term studies lasting less than three months at these schools do not require a student visa, tourist visa is sufficient.
Different government departments, some organizations and educational institutions offer short term exchange programs to secondary and post secondary students. The purpose of such programs is to allow foreigners experience life in Japan and study. These programs are limited to countries and students of institutions that have bilateral agreements with Japanese universities or government. You have to check if such agreement exists between your country or institution and Japan.