For years, industry watchers speculated that Nintendo could rule mobile if it would only make games for smartphones and tablets. And based on how well Miitomo has done in its first week in Japan, we now have proof that the storied Japanese gaming company is primed to succeed on mobile worldwide.

Miitomo hit No. 1 in all categories (not just games) for free iOS apps in Japan today, app marketing intelligence firm Sensor Tower told GamesBeat. It’s tracking Miitomo on its own platform, and the data comes from Japan’s Apple store. Mobile gaming is a $34.8 billion industry worldwide, and $6 billion of this comes from Japan. Nintendo has struggled with its Wii U home console, and sales of its aging 3DS handheld have been tailing off.

This social game knocked GungHo Online Entertainment’s Pazudora Radar from the top spot. That title is a riff on Puzzle & Dragons, itself one of the most profitable games on the Japanese mobile market.

Miitomo isn’t in the U.S. app store yet, but GamesBeat did download it from Japan on Android to give it a spin, as it already has an option to play in English. The big thing about Miitomo is that it is essentially Facebook or Twitter by way of Nintendo. If we lived in a universe where the same company that invented Mario also invented social networks, Miitomo is what we’d get.

You start by creating or linking Miitomo to your My Nintendo account, which is the publisher’s new network service that will also appear on its console devices. You can then either make your Mii or import it from your 3DS or Wii U using the QR-code feature. After that, you’ll want to find some friends by linking Twitter or Facebook to the game.

According to Sensor Tower, apps that usually hit No. 1 in Japan receive more than 100,000 downloads a day.