Should an international student wish to remain in Japan after graduation for purposes other than continuing searching for employment, he/she must change his/her status of residence from "Student" into a type of status according to the type of activity undertaken. You are strongly advised to go through the procedures to change your status of residence as soon as possible.
Even if the period of residence previously granted under the "Student" status has not yet expired at the time you graduate, you must apply for a change of status of residence in case you wish to remain in Japan, as your "Student" status is no longer valid once you have graduated.
Please keep in mind that failing to go through the procedures to change your status of residence is considered illegal residence