We also rent a persimmon orchard and manage that. I am currently investigating a kind of Peruvian Potato that is popular among health food enthusiasts and getting top dollar at the moment, which supposedly grows well in our local area. Almost everyone around us in this part of the country raises the big Kyodo table grapes. Other grapes are a possibility, a wine grape vineyard is another if this is your dream. There are some local wineries in the vicinity, why not start one.
Foreigners can attract a lot of attention in Japan if they want to.