Setsumatsusha
Sessha and massha, also called eda-miya are small or miniature shrines entrusted to the care of a larger shrine, generally due to some deep connection with the enshrined kami.
The two terms used to have legally different meanings, but are today synonyms. Setsumatsusha can lie either inside or outside the main shrine's premises. Setsumatsusha are usually 1x1 ken in size. They can however be as small as beehives or relatively large and have 1x2, 1x3 or even, in one case, 1x7 bays.
History
The practice of building sessha and massha shrines within a jinja predates written history. The earliest setsumatsusha usually had some strong connection to the history of the area or the family of the enshrined kami.During the Heian period, Ise Shrine used to make a distinction between the two types based on whether a shrine belonged to the Engishiki Jinmyōchō list or to the Enryaku gishikichō list.
From the Japanese Middle Ages onwards, at other shrines popular kami like Hachiman, Inari or Gozu Tennō were often enshrined in setsumatsusha, but no clear distinction between the two terms was made. From the Meiji period to the Second World War, a shrine dedicated to family members of a kami, to the violent side of a kami, or the kami of the region where the main shrine was, were to be considered sessha with a higher rank than the rest, which were called massha. When the ''Modern system of ranked Shinto Shrines shrine ranking system was abolished in 1946, legally the distinction disappeared, but both terms remained in use out of habit.
Betsugu are another kind of auxiliary shrine their relationships to the main shrine are similar to that of Massha and Sessha. The term is most notable for the extensive betsugu at Ise Grand Shrine.