Micho no eki, Roadside station is a government designated rest area, located along national roads throughout Japan. Michi no eki is a place where you can eat, buy and have a rest.
Highways(drivers have to pay the tolls) have rest areas called Service area or Parking area but it is similar version for roads without tolls. Not only lavatories and vending machines are located at the roadside stations, but also intend to promote local tourism and trade, which means local products are sold at the stations.
Local products can be snacks, foods, souvenirs and also vegetables from the local farmers. Not only the tourists but also the local inhabitants will come and buy the products.
The difference between Japan and Europe is that Japanese are much keen on souvenirs. Souvenirs can be either food or goods. Therefore almost all cities, towns and villages have at least one product which are representing them. Which means if you travel to 5 places, you can buy at least 5 local products during your stay in Japan(It does not mean that you can buy 5 different T-shirts or 5 different magnets).