Bandai Namco is releasing free Ninja Box Pack DLC for Taiko no Tatsujin: Drum 'N' Fun, and it's due out Dec. 12th, 2019 in Japan. This DLC will include the game’s theme song, as well as the main character Tonkachi. Don Chan will also be added to Ninja Box at a later date.
A third collaboration is for Tsuri Spirits Nintendo Switch Version, which will see Don Chan and Tonkachi starting Dec. 9th, 2019 and running until March 31st, 2020. Characters from all three games will also appear in a Ninja Box web anime episode.
Finally, the Donda Pack -Higetsu- (priced at ¥550) and some individual songs (priced at ¥165 each) will be added on Dec. 12th, 2019 as well.