Mitsuharu Shimamura is on a crusade. The credo he preaches is the "miracle fruit," a plant native to West African countries such as Ghana and Nigeria.
Every time he lectures about this unique fruit in classrooms, children raise their hands one after another to ask for another cup of sour lemon juice, or to bite into another whole lemon.
This isn't because the kids have unusually strong constitutions.
When they eat or lick the plant's tasteless red berries, any sour thing they eat or drink a minute later tastes sweet for about two hours.