The whole work is made by one piece of Japanese paper (Washi). The paper is cut into many squares but they are not completely separated into individual pieces; they share the corners. At the contact points, two cranes touch each other's wing. Lower cranes are smaller. This ratio is logical consequence of dividing a piece of paper into multiple squares.
This model is made from a piece of Washi, which is cut into same size of squares sharing their corners.
Seikaiha originally refers to a kind of Kagaku, Japanese traditional music and dance. In old times it was local music of Seikai region in China. The wave pattern used for costume to dance to Seikaiha is also called "Seikaiha". This design is repeated pattern of wave.
You must choose strong paper made from long strong fiber, or the shared corners may tear apart.
Instructions to fold above models are written in "Senbazuru Orikata (One Thousand Cranes Origami)" by Kunihiko Kasahara.