That is quite beautiful. I'm a ligature nut, and -- correct me if I'm wrong here -- I think it's pretty rare to see a ligated sans. Yes? It's beautiful here. Nicely done, Rugen.

It's not as uncommon as you might think, largely because most people don't/can't use them, but they're not as common as serif faces with ligatures. I suppose this is partially due to serif faces being the predominant book typography choice. But I'm sure the actual reason is much more complex and much less logical, as typographic history tends to be.