The Hatchokura-dori (Hatchokura Street) is home to some of the oldest and most famous miso factories in Japan. The miso produced there is known as hatcho-miso, after the area. It is a special miso belonging to the mame-miso category, as it is made by 100% soy beans, natural salt, and pure water. It takes 2 years to brew in old huge cedar tubs.
The 500-year-old miso factories, Maruya Hatcho Miso and Kakukyu Miso Factory, both provide factory tours. At the latter, there is a miso-making museum that is worth your visit. In this museum you can see the huge cedar tubs where the soybean paste ferments, as well get informed about the whole process of miso making.
Make sure to bring a Japanese friend with you or a tour guide because the tours are held only in Japanese! Then, enjoy some miso ramen afterwards to complete your miso experience.