This is a twice-brewed soy sauce. Koji is made from soybeans and wheat and aged two years into raw soy sauce. Then koji is added to that soy sauce, in place of the water an ordinary batch would use, and the whole thing ages another two years.

Four years, for one bottle, and half of that spent fermenting something that was already a finished product. What comes out is dark and thick enough to cling to a slice of raw fish.

The salt content runs twelve to fourteen percent and the nitrogen, which is where the savor sits, is high at 1.6 to 2.5 percent. Long aging takes the edge off the salt, and what registers instead is sweetness.

The name comes from the Edo period. A merchant in Yanai presented the sauce to the lord of the Iwakuni domain, who is said to have pronounced it kanro, nectar, twice over, and the word stuck. The maker is given as Takada Denbei, working around the Tenmei era in the 1780s, which puts the sauce at over two hundred years old. Yanai sits at the western edge of the Iwakuni domain and grew wealthy on shipping; its white-walled merchant streets are still standing as a preservation district, and the sauce is sold along them. It even turns up in the old railway song.