Yeast

Kōbo (酵母) is a unique crop produced within Wall Sheena.

Usage
The yeast produced in Wall Sheena bears resemblance to a lump of fermented soybeans the size of a human head. These batches of yeast are stored in sheds or tents along with other goods such as wheat, soybeans, and dry-cured meats in order to drastically slow the rate of decomposition.

The yeast stored with these various goods appears to transform said goods by currently scientifically unexplained means.