A merchant in southwest Trademond, his stock consists of formulae.
His store will not be open until one point in the Save the Crops quest. After that quest is resolved, he will be available indefinitely.
20% after Date With Hermann 4
20% after Fake Marriage with Hermann (stacks with the above to 40%).
He has 3 associated lewd scenes. The first one is available as part of the Save the Crops quest, instead of paying him 2000g for the formula. If this opportunity was rejected, the other lewd scenes will not be available.