So (蘇) was a type of dairy product made in Japan between the seventh and 10th centuries. The method of creation is noted in Engishiki as so acted as a gift in kind to the emperors. Daigo was produced by further processing so. The first record of so was made during the era of Emperor Mommu (697-707 AD). Tennyakuryo, then a part of the Ministry of Imperial Household, was responsible for the production of so. It was used as a medicine and as an offering to gods. The production sites known to date include Ajifu in Settsu (current Higashiyodogawa-ku in Osaka). So is made by solidifying layers of milk skin. The flavor is light, similar to that of cottage cheese.