If you’re interested in the field of architecture then you may want to look into the continuing education programme offered by the American Institute of Architects in Tokyo:
The Canadian university McGill has its own campus in central Tokyo and runs an MBA programme from there. The classes take place on weekends, so you can do the course even if you’re working full-time. Classes are taught in English and the academic year begins in June. For more information:
You may want to consider taking classes through one of Tokyo’s E-Learning
centres:
http://www.weekender.co.jp/new/education/e-learning-schools.html">
The Japan Adult Education Directory is a useful resource
too:
http://dir.japandirectoryonline.com/dirs/?catid=320195
Your local ward office can also give you more information about continuing education in Tokyo.