[Nyororin]

I don`t believe there is any sort of limit on the hours you can work...

However, the big question is; Do you speak Japanese?

If you do not, the chances of finding any position short of English teaching or the like are pretty close to none. Companies who need professionals and do not care if they can speak Japanese generally hire them abroad and bring them to Japan. Unless you are also fluent in Japanese, the chance of being picked up on a temporary visa is almost 0.