So (Japanese: 蘇, originally Japanese: 酥) was a type of dairy product made in Japan between the seventh and 10th centuries.[1] According to Engishiki, so was introduced from Baekje, and acted as a gift in kind to the emperors.[1] Daigo was produced by further processing of 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.[2]