Bernard Castelain is a French chocolatier. He is also very good at his job.
Some friends got me this. I don't know from where. I think I need to find out.
Basically, here's the deal: a 99% bar is usually indistinguishable from a 100% bar, because 1% sugar is just not very much sugar. But Castelain throws in some extra cocoa butter, in addition to the ground beans, in order to cut the bitterness. This is the strategy used by Devauve et Gallais to great success. It works here as well.
Bottom Line: Delicious, edible 99% chocolate.