Another angle: Sanpo might be a typo for Sanpū, which I don't think is a brand. Maybe Sanpo is a line within Sapporo. Or maybe it's a different company. Or perhaps the user is referring to a Japanese whisky that's 9 years old, 6 liters (which is an unusual size, as standard is 700ml), and named Sanpo. But 6 liters is huge, so maybe the user made a typo. Maybe they meant 6L but actually meant a more typical size. Or maybe it's a large cask or something.