After guiding us at the site of Shimbaru-Nuyama Mounded Tomb Group, Takemoto-san took us to Tsuyazaki Sengen, a small township once served a commercial centre of the region, where "Aino-ie" or "Indigo House" is located. Built in 1901, the house is registered as an tangible cultural property.

Tsuyazaki Sengen Ethnological Museum”Ai-no-Ie House” - Cross Road Fukuoka

A street of Tsuyazaki Sengen. To the left is "Aino-ie" indigo house.
 

The front appearance is simple yet tells us a lot of designing innovations.
For example, you can see that upper sides of the house wall are protruded; they are called udatsu, meaning the fire-proof wings typically adopted to the houses built in the crowded city centers in Japan until Edo-period.
 

Another mechanism of the house to let fresh air come inside. 
The window consists of "sanmai-ita," three boards of wood using no nails at all.
In fact, the entire house was built without a nail.
 

"Ranma (a wooden panel with openwork carving) is not only beautiful as a decoration but also useful for the air circulation," the volunteer guide lady told us.
 

We met a knowledgeful guide at Aino-ie.
 

Explaining an amazingly well-designed storm shutters storage. 
 

The storm shutter storage has a door on it.
 

So people's free-flow was not disturbed even after closing the shutter.
 

Overseeing the courtyard.
Dying clothes in indigo avoid worms and also strengthen the life of the kimono, which made it custom for the people until Edo periods. Therefore, the dyers were like mandatory service providers at that time and thus never suffered from business declines.
The term "Japan Blue" comes from this indigo dying culture in Japan, the guide lady told us.

NHK - Begin Japanology: Aizome (Indigo dye)