In the Edo era, this building of the Japanese oil dealer had the largest area among dealers'houses in Japan. As the museum of Japanese oil dealers, Hongura (main storehouse) which is said to be built in 1701, Kanjogura (counting storehouse), Komegura (rice storehouse), equipment warehouse, and employees'room are displayed as they were. Business tools and household commodities used at that time, and curiosities brought by the owner from Nagasaki area are also displayed. Muroya-no-sono has been designated as an important tangible folk-cultural property.

This building, which was completed in the late 18th century, has been designated as an important cultural property because of the typical merchant house style in the mid-Edo era. The building has the structure of the Irimoya style, and is two-storied godown, and has the Hongawara on the roof. At the front of 1st floor, there is a “Bucho” which can be fully opened as necessary. In addition, detail consideration is given to install the sliding door which was made of the clay for fire prevention.

A part of this Soy Store Room where the local specialty “Kanro soy sauce” is being produced is opened as a museum. Putting the koji again into the soy sauce already produced produces “Kanro soy sauce”. The soy sauce was praised by Kikkawa who had governed Yanai in the Edo era, saying “Kanro, Kanro” (sweet! sweet!). This is the origin of this soy sauce's name. Visitors can see the actual soy sauce tub (approx. 5410 liters per tub), equipment of soy sauce production, and data related to the trading in the past to touch some part of the food culture.

This building is equipped with a music box which plays a gentle sound in Retoro Street. The songs from this music box were original those and composed by Isao Hashimoto, who is the only music box tune composer in Japan. 5 songs are played in order in Retoro Street. With a disc music box installed in the center, you can listen to an excellent sound at 100 per song.

A gift shop and restaurant standing beside the street with the shirakabe (white wall). In this gift shop, Yanai traditional crafts such as “Yanaijima” (cotton fabric) and “Kingyo Chochin” (goldfish-shaped lantern) are for sale, and visitors can see the demonstration of “Kingyo Chochin” creation by its professional. In the restaurant, “Chagayu” (rice gruel with tea), which is local specialty of Yanai, is popular as it is simple and has deep taste. Also, you can eat “Hannya Gozen”, which is a seasoned steamed rice with Seto shellfishes which are caught in the sea close to Yanai.