Shiga was originally known as Ōmi Province before the prefectural system was established in the 17th century and Lake Biwa, which accounts for one-sixth of the total area of Shiga Prefecture, was also previously referred to as Ōmi[the current name, Lake Biwa, comes from the fact that its shape is similar to that of the Japanese lute called a Biwa].  
In 667 AD the Ōtsu Capital realm started under Emperor Tenchi and he moved the capital Ōtsu from Asuka [Nara  Prefecture] to the shore of Lake Biwa, making Ōmi the center of the nation.  However, when the Emperor died a few years later Ōtsu Capital was abandoned only five years after it was established.

Shiga Prefecture centers around Lake Biwa as there is a tectonic basin [a landform characterised by relatively steep, mountainous sides and flat floors] known as the Ōmi Basin.  In this case, part of the basin has filled with fresh water forming Lake Biwa and the alluvial plains surrounding the lake.  These alluvial plains [a plain formed by sediment being deposited from rivers, generally from periodic flooding] are narrow on the western side but wider on the East and have a long history of cultivation as rice paddies.

The harvests in Shiga Prefecture are generically called Ōmimai (Ōmi Rice) and the quality is exceptional because of the climate, rich ground and pure water.  The area grows many famous rice such as "Koshihikari," "Kinuhikari" "Nihonbare" and such new varieties as "Yumeomi," and "Akinouta." 

Founded in 1917, Ōmi Shuzō is situated on the East side of Lake Biwa in Higashiōmi, and so is able to use the high quality rice that grows around Lake Biwa as well as the soft water that Shiga is known for.  The Sake from Shiga often has a sweet, mellow taste because of this famous water. Ōmi Shuzō’s Sake is always scarce due to it’s very small production size, but fortunately they have a treasure trove of incredible Koshu [aged] Sake.