Splatoon has been one of Nintendo's most successful games in the past few years, and sales still haven't slowed down almost a year after its initial release. The latest Japanese sales data on Splatoon indicates that the game has sold a total of 1,356,993 copies in the region. To put this into perspective, the Wii U has only sold about 3.13 million units in Japan since its release, so this means that over 45% of Japanese Wii U owners have bought a copy of Splatoon. For an entirely new series, those numbers are astounding. This makes Splatoon the best-selling new IP to hit consoles in Japan since Wii Sports in 2006.
Splatoon's Japanese sales have always surpassed Nintendo's expectations, even outselling Mario Kart 8 and Super Smash Bros. Wii U in the first 18 weeks after its release. Outside of Japan, the last sales official report claimed the game had sold over 4 million copies worldwide, which gives it an attach rate of over 30%.