I want to live in Japan for at least a year while taking online college cles. What can I do for my visa?

You'd better start doing a lot of research on the cultures and history of the country. Japan historically do not welcome foreigners to live permanently on their soil, thats why you can barely see or hear English used in Japan. Also Japan was one of the hardest hit in the current worldwide recession, it has been in recession for 20 odd years, and has the largest debts on earth, similar to that of Africa. Even if can stay there as a foreigner, be prepared that the chance of landing a good job is close to zero.