To study in Japan, you have to pass all the necessary immigration processes. Then it is so important to arrange and get the two important documents, VISA and Status of Residence.
When you enter Japan, you will be required to submit the VISA, which is the entry permission by the Ministry of Foreign Affairs of Japan. The way to get depends on each country, so you should check the website of the embassy of Japan in your mother country or Ministry of Foreign Affairs of Japan.
Cf. Ministry of Foreign Affairs of Japan Official Website: here
Status of Residence shows the legally categorized types of activities of foreign people, while they stay in Japan. Within the range of each Status of Residence, you will be allowed to involve a certain activity, for example, studying at educational institutions, or working in a specific field.
Cf. Ministry of Foreign Affairs of Japan Official Website: here
If you need more detailed information, please check the official website of Jasso:here