Founded in 1723, nearly 300 years ago, this brewery has a rich history of craftsmanship. The brewing water comes from underground sources near the coastline, passing through shell layers. With a hardness level of 13–15, it is considered one of the hardest waters in Japan. Using this hard water in the traditional yamahai brewing method, the resulting sake is full-bodied, rich in umami, and has a bold, well-rounded acidity. Additionally, the brewery takes pride in using locally grown rice, with most rice sourced from Chiba Prefecture. Combining Chiba’s rice with Onjuku’s unique water and the time-honored yamahai method, this sake is a perfect representation of "classic Japanese sake." Now, this traditional sake is going beyond Japan’s borders, playing a key role in spreading the culture of sake to the world.