Shunsuke Sakaki is a part-time university lecturer on Western European history. Ema Sakiyama, his student and Roppongi’s top hostess, asks for his help in settling a dispute with a customer who sent back a glass of champagne. With help from Rin, Ema’s friend who is oddly knowledgeable about champagne, it looks like Sakaki is gradually coming to understand the profound world of champagne, but…?