Since the early 1990s, Steven Reed and Gary Cox have changed our understanding of Japan's multimember SNTV electoral system, by highlighting its institutional effects similar to what is known as Duverger's law in the Anglo-American context. While we offer some additional evidence to consolidate their findings, we also address an issue left unexplored in these studies, namely the role of partisan information. Under Japan's system, party labels matter in elections. We show that, while Japanese voters are generally willing to abandon the candidates without affiliation with established parties, the partisan effects produce constraints for strategic coordination.