Vertical, narrow prints are a by-product of traditional Japanese architecture, which offered very few solid wall surfaces. Many times, the only solid surface available for the hanging of pictures, were the structural posts which held up the roof. "Pillar prints" became a genre unto themselves and were referred to in Japanese as hashira-e or tanzaku.
The design of pleasing compositions within such a constrained format is a serious challenge for the artist. Yoshimoto Gesso and Shoda Koho, the artists who designed the prints in this series, have certainly risen to this challenge and produced a wide variety of wonderful designs.