Taiko no Tatsujin: 15-shuunen Kinen Short Animation
Type: ONA, Episodes: 1
Aired: Jun 25, 2015
Studio: Studio Ghibli
Source: Game
Rating: G - All Ages
Synopsis:
Toshio Suzuki and Studio Ghibli produced the short to commemorate the 15th anniversary of the Taiko no Tatsujin (Taiko: Drum Master) rhythm game series. The short features Taiko no Tatsujin characters Don-chan and Kacchan, as well as an original mouse character. The short will also be broadcast as a TV ad later. 

(Source: ANN)