Taiko no Tatsujin: The Drum Master!

This achievement is for cumulatively hitting 10,000 "DON" notes, which are the red notes.

Both the small "Do" and the larger "DON" notes count towards the 10,000 despite the description saying only "DON" notes. Also, getting a timing of "good" and "ok" will count towards your progression.

This achievement should come naturally as you're working towards other achievements as red notes are by far more common than blue notes on every difficulty, so even Easy players should get this without having to grind. As a player who bounces between Easy and Normal, I unlocked this after about 75 songs so you should be able to obtain this before getting the achievement for playing 100 songs.

If for some reason you don't have it unlocked or just simply want to grind this achievement out early, I recommend playing songs with a higher star rating as they typically contain more notes. Anime songs seem to be shorter as they tend to stick to their 1:30 openings as presented in their shows but most songs are about 2 minutes anyways. Lastly, make sure the Inverse mode is set to OFF to get the most red notes.

Good luck and happy hunting!