(Extract from "Guidebook for International Students and Researchers")
For foreign nationals staying in Japan for 3 months or longer, residence card is issued upon their arrival to Japan and entry through Narita, Haneda, Chubu or Kansai International Airports.
When you receive your residence card, please carry it with you whenever you leave home. You must present it when an immigration inspector, immigration control officer, the police, or some other administrative officer of the government asks for it. Note that the residence card will not be issued if you are staying in Japan for 90 days or less.
2． Renewal of Residence Period
The maximum period of stay in Japan as a student under the original visa is four years and three months. However, you can apply to renew the visa at the Immigration Bureau before its expiration. Please contact the Immigration Bureau information centers.
http://www.immi-moj.go.jp/english/info/index.html (Link will open in a new window.)
Required documents for the renewal
 application form for renewal of visa (available at the Immigration Bureau service counters),  one ID photo (4cm x3cm, taken within last 3 months),  residence card,  Passport or Certificate of Eligibility,  permission to engage in activities not specified in status of residence, and  evidence document for financial support during your stay in Japan, and  the application fee(JPY 4,000). You may also be requested to provide additional documents.
http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/03.html (Link will open in a new window.)
3． Change in your Residence Status
If you graduate or leave the university, college, or Japanese-language school you are affiliated with and enter a different school, you must submit a notification concerning the new school to the Immigration Bureau within 14 days after entrance to the new school. Please visit Ministry of Justice Webpage:
http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/02.html (Link will open in a new window.)
Upon graduation, you must promptly leave Japan since your eligibility for residence as a student in Japan is lost regardless of validity period. The same shall apply upon withdrawal, dismissal, or a leave of absence from the university. If you wish to remain in Japan after graduation for job search and other reasons, it is required to change your residence status at the Immigration Bureau. Please inquire at the TUAT administration offices.
4． Temporary Leaving Japan
If you intend to leave Japan temporarily during summer break or at other time, you must inform your academic advisor or your department chair and administrator. Please use form attached to the "Guidebook for International Students and Researchers" below.
http://web.tuat.ac.jp/~intl/download.html#guideintl (Link will open in a new window.)
As a rule, international students with residence card do not need to apply for permission to re-enter Japan for the purpose of continuing their permitted activities in Japan, as long as they return within one year. However, when you leave Japan, you will always be required to present your residence card.
Under this re-entry system, students who leave Japan cannot extend the validity period for re-entry while in overseas. You will lose your residence status if you do NOT return within one year. If your period of stay is expiring in less than one year after your leave, you will need to re-enter Japan prior to the expiration date.
5．Part-time Jobs (Engagement in Activities not Specified in Residence Status)
With residence status of “student”, you are permitted to engage only in activities that pertain to your academic studies and research while in Japan. To work part-time, you need to apply to the Immigration Bureau for permission to engage in activities not specified in your residence status. Please visit the Ministry of Justice webpage for details or contact the Immigration Bureau. http://www.immi-moj.go.jp/english/tetuduki/kanri/shyorui/09.html (Link will open in a new window.)
Please note that no such permission is needed to work on campus as a teaching assistant, research assistant, tutor, or other similar posts.
As a rule, you can only work up to 28 hours per week while school is in session, and a maximum of 8 hours per day during the summer, winter, and spring breaks. You are NOT permitted to work at certain designated entertainment businesses or places related to such businesses. International students sponsored by the Japanese government (MEXT scholarship students) are not allowed to engage in activities not specified in their residence status.
For other legal procedures, please check Ministry of Justice Webpage:
http://www.immi-moj.go.jp/english/tetuduki/kanri/hituyou_syorui.html (Link will open in a new window.)