Gozenshu is sake (Japanese liquor) which was brewed and delivered to people such as seii taishogun (literally, "great general who subdues the barbarians") and daimyo (Japanese territorial lord) during the Edo period in Japan as a drink for so-called "tono-sama (a person with higher rank)". When no special mention is made in the context, it refers to the gozenshu for the Tokugawa Shogun family.
Naturally, it was of the best quality among the sake of the time and was ranked above katahaku (sake brewed from polished white rice and unpolished rice) and morohaku (sake of 100% polished white rice) in quality. It was also known as "jo-morohaku (sake of 100% polished white rice, literally meaning 'better-quality than morohaku')".
Gozenshu for the Tokugawa Shogun family
In 1740, the ''Kenbishi Shuzo" (Kenbishi Sake Brewing Company, Limited) which brew Itami sake was designated as the brewery of gozenshu for shogun.
Sake produced in Kyoto included those which would today be considered as falling under mislabeling or misleading representation of products, such as "shoka gozenshu (sake for the feudal lord for families)", "御前酒" (which can be read as "gozenshu" but uses a different Chinese character for "zen" from the actual gozenshu), and "goyoshu (sake especially made for someone in high rank)", as many sake breweries increasingly tried to take advantage of the fame of "Kenbishi" by placing confusing names that are similar to the gozenshu for the shogun family, on their sake barrels. An order was issued in Kyoto to strictly prohibit such activities.
Gozenshu in each domain
In each domain, gozenshu referred to the sake which was drunk by the lord of the domain.
The selection of gozenshu differed according to the lord of each domain; for gozenshu, some daimyo selected Itami sake like the shogun family, or at least the sake from the same Sessen-juni-go (the twelve sake brewing districts in Settsu Province and Izumi Province shipping for Edo) where the Itami sake was produced, and some others selected the sake which was the local specialty of the hometown, for the purpose of industrial development of his own domain.
In the latter case, although the gozenshu was supposed to be the top quality sake brewed by the clan, some clans had poor brewing techniques despite many efforts, and could not sell their gozenshu to other domains; in such case, the lord was drinking it with some tolerance in terms of the taste, so as to improve the finances of his domain.
The sake brewery of the hometown which produced gozenshu was called "goyo zakaya (official sake brewing family)", and sakashi (sake brewer) and toji (chief sake brewer) who were authorized by the domain for production were called "sakatsukasa" ("sakajiko" in the Nanbu Domain, etc.). While this sakatsukasa is often confused by the public with the sake-no-tsukasa (also called "miki-no-tsukasa"), or historical sake brewing by the Imperial Court during the Asuka and Nara periods, they are actually completely different concepts.
Goyo zakaya is said to have begun with the first Mataemon KAYANOMORI, who was of the Nara school of sake, which has the tradition of soboshu (sake brewed in major temples) that was known as a famous sake-brewing district before Itami became famous; Introduced by Munenori YAGYU, Masamune DATE ordered him to make the jonai-zume-onsake-goyo (making of sake especially for the feudal lord inside the castle) in Sendai Domain in 1608.