The Sh?s?-in () is the treasure house that belongs to T?dai-ji in Nara, Nara, Japan. The building is in the azekura log-cabin style, with a raised floor. It lies to the northwest of the Daibutsuden (which houses the Great Buddha). The Sh?s?-in houses artifacts connected to Emperor Sh?mu (701-756) and Empress K?my? (701-760), as well as arts and crafts of the Tempy? period of Japanese history.
The construction of the T?dai-ji Buddhist temple complex was ordained by Emperor Sh?mu as part of a national project of Buddhist temple construction. During the Tempy? period, the years during which Emperor Sh?mu reigned, multiple disasters struck Japan as well as political uproar and epidemics. Because of these reasons Emperor Sh?mu launched a project of provincial temples.[better source needed] The T?dai-ji was appointed as the head temple of these provincial temples. Emperor Sh?mu was a strong supporter of Buddhism and he thought it would strengthen his central authority as well. The origin of T?dai-ji's Sh?s?-in repository itself dates back to 756, when Empress K?my? dedicated over 600 items to the Great Buddha at T?dai-ji to express her love for her lost husband, Emperor Sh?mu, who died 49 days earlier. Her donation was made over five times across several years, then stored at the Sh?s?-in. During the Heian period, a large number of treasures, consisting of items and instruments used in important Buddhist services were transferred from a different warehouse called the Kensakuin to the T?dai-ji.
After the Meiji Restoration, it came under the administration of the national government, and since World War II has been under the administration of the Imperial Household Agency. It is on the UNESCO register of World Heritage Sites as one of the Historic Monuments of Ancient Nara. It is also a National Treasure of Japan.
The building is in the Azekura Zukuri log-cabin style, with a floor raised to about 2.5 m takayuka-shiki (). This is an architectural style that was mainly used for the construction of granaries and storehouses. Some distinctive features of this building style are the triangular, wooden beams that come together in the corners, as well as the fact that it was assembled without using any bolts nor nails. This could be slightly surprising for its height of 14 m, width of 33 m and depth of about 9.3 m. However, it was a logical and smart step. As a result of assembling the storehouse without bolts or nails, the structure became very flexible and able to withstand earthquakes, a phenomenon of nature that Japan was already well acquainted with during Nara period. The Sh?s?-in is also the only building to survive the Siege of Nara in the Heian period. The exact construction date is unclear, but construction works probably started soon after the empress's bequest in AD 756 and definitely were finished before AD 759, when the bequest items storage lists were complete.
Since the Sh?s?-in was to be a repository for (valuable) objects, it was constructed quite ingeniously to create a natural climate regulation system. This natural climate regulation system was created by elevating the floor to a height of 2.7 m. This made circulation of air underneath the building possible and protected the structure against humidity at the same time. In addition to this, during the first few decennia after its construction, the triangular beams of the Japanese cipres might have functioned als a natural regulator of humidity and temperature. The artefacts themselves were stored away in chests made from Cedar wood that's known for its durabilitiy. These chests were 90-110 cm long, 60-70 cm wide and 40-50 cm high. Not only the building itself but also these chests were elevated from the ground. All these nifty adjustments made it possible to preserve the treasures in perfect state.
The Sh?s?-in today holds around 9,000 items, leaving out items that are yet to be classified. The treasures that were donated by Empress K?my? were stored in the Hoku S?, the Northern part of the Sh?s?in. From the very beginning this part of the Sh?s?-in has been sealed by the imperial family. One was only permitted to enter with explicit permission of the imperial family. While a lot of the items of the collection are remainders from the 8th century and of domestic production, like art or documents, there is also a variety of items originating from Tang China. Other materials comes from as far as India, Iran, Greece, Rome and Egypt.
Although these collections are not open to the public, selections are shown at Nara National Museum once a year in autumn.
The objects and treasures that have been stored in the Sh?s?-in can be divided into the following categories. 
Apart from these objects for everyday use, pieces of writing Shoseki have also been preserved in the Sh?s?-in. These pieces of writing can tell us detailed stories about Nara period's society, social life, the population, social, cultural and economical activities.
Since 1994, the Imperial Household Agency's Office of the Shoso-in Treasure House, which is responsible for the administration of the repository, has been producing exact reproduction of ancient Nara textiles. Apart from the appearance and colour, care has been given to reproduce the production and weaving style. The silk is donated each year by Empress Michiko, who personally runs the Momijiyama Imperial Cocoonery at Tokyo Imperial Palace.