I have been working in Japan for almost 4.5 years and my visa status is "Engineer".
Now I want to enroll to a graduate school... to be specific, join a weekend MBA program. Do I have to change my visa status to "Student" and quit my full time job ??
Is it possible to maintain my current visa status, working full time and also study weekend MBA program?
Please suggest me where can I get some information
Yes I think you can do your education while working. Its called as 社会人大学院。 As you will be enrolled as a 社会人 into the university, I think there's no need to change your visa status (from 'engineer' to 'student').
You can get more clarified information from 入局管理局Information center.
http://www.immi-moj.go.jp/info/index.html
Call to the nearby center and get the information.
Good Luck !!