Yo-kai Watch Busters: Moon Rabbit Team announced for 3DS, coming to Japan in December.

[TheWPCTraveler]

So...

Yo-Kai Watch (2013)
Yo-Kai Watch 2: Head/Founder (2014)
Yo-Kai Watch 2: Headliner (2014)
Yo-Kai Watch Busters: Red Cat Team/White Dog Team (2015)
Yo-Kai Watch Dance (2015)
Yo-Kai Watch Busters: Blue Rabbit Team (2015)
Yo-Kai Watch 3 (2016?)

Three (five) mainline retail releases.
Two (four) major spin-off retail releases.
All in the span of just three years.