Back in October last year, Nintendo revealed that its upcoming smartphone game – the company’s first entry into the mobile gaming market – would actually be a “communications application that helps friends share fun personal facts and interests.”

The news wasn’t well received, to say the least; not only were fans unhappy, but Nintendo’s shares fell by almost 9 percent, and DeNA, the Japanese company who co-developed the game, saw its shares fall 15 percent.

Miitomo was finally released in Japan last Thursday after its original launch date of late last year was postponed so Nintendo could promote the app. It seems that, despite not actually being a game and featuring none of the company’s iconic characters, Miitomo has been a resounding commercial success; three days after release, it had been downloaded one million times by users on Android and iOS.

Early critic opinions of Miitomo had been mixed, but the overwhelming majority of those who purchased the application left glowing reviews on the app stores. Nintendo’s offering quickly moved to the top of Japan’s iOS charts, pushing popular messaging app Line to number two.

Miitomo is a free-to-play title inspired by the 3DS’ Tomodachi Life series. It combines social elements with mini-games and character customization, which is where the in-app purchases come in. While it’s only available in Japan right now, it will arrive in other countries, including the US, at a later date.

Nintendo will release four more smartphone titles over the next 12 months. It’s promised that these will be games, rather than social apps, and some will feature famous characters. Nintendo hasn’t said which of its iconic stars will be in these titles, but don’t be surprised to see a certain Italian plumber make an appearance.

Nintendo’s shares jumped 8.1 percent after news that Miitomo had hit the 1 million download mark. The app's success also helped DeNA's shares climb by 6.5 percent.