Traditional rooms in Japan, including rooms in Tondaya, are decorated with hanging scrolls. And the image or saying on it depends on different things, for example, season, case or kind of room. 

A kakemono or kakejiku, a scroll painting or calligraphy, is peculiar to Japanese culture. These scrolls made of silk or paper are stored being rolled up, because paint and silk are very sensitive to environment, and are hung on special cases or seasonally.

Kakemono is usually used as part of the interior decoration of a room and also in a teahouse to set the spiritual mood of the traditional tea ceremony. In this case kakemono bears some calligraphy of wise saying.

So I again encountered about it, that many customs in Japanese culture are attributed with seasonal changes in nature and many things have spiritual meaning.