Ranma (欄間) is transom in traditional Japanese buildings. It is a rectangular opening just above doors to light flow in and to allow ventilation, as well as to add decoration.

The ranma can be fitted with shoji, lattice, and wood openwork carvings.

Ranma made from Shoji is refered to as ranma-shoji (欄間格子), and ones made with lattice are called ranma-koushi (欄間格子). Sometimes ranma are simply referred to just as ranma

Ranma can be found above the genkan, between the engawa and the interior of a building, or under the ridges of a gate, for example.

— History

During the Nara period, ranma were used to allow light into shrines and temples. Later on, it began to be used in aristocratic homes. After the Edo period, it was introduced and used in ordinary homes.

Ranma-shoji were popular from the 12th century to the 14th century, during the Muromachi period. During the 15th century, flat openwork, called sukashibori (透彫), became popular. Ranging from the later half of the 16th century to the end of the 17th century, ornate trees, scenes, and figures were carved into ranma.