Taiko no Tatsujin: The Drum Master!

This achievement is for hitting a cumulative total of 5,000 "KA" notes. "KA" notes are the blue notes. Both Good and OK hits will count towards this achievement.

If you're like me and don't prefer to play a difficulty higher than Normal because you're using a controller, this achievement might seem next to impossible as "KA" notes rarely appear on lower difficulties.

Luckily, the game has an "Inverse" option in the menu that will change all red notes to blue and vise versa (Please note that all balloon and party popper notes will still use the red "Don" to pop them in this mode). This makes the achievement much quicker to achieve on easy and normal.

To select the Inverse mode, on the select difficulty screen press to bring up options then turn Inverse to on. This will show an icon with a two-way arrow. Make sure to press to confirm your selection and check to make sure the icon is present above your gamertag nameplate in the bottom left before starting the song.

As far as great songs to boost, I recommend ones with higher star ratings since they have more notes and every song in the game is about 2 minutes long. Personally, I used the last vocaloid song "Hana Oto Urabyoushi" as there are over 200 "KA" notes on Nomal and I found the song fairly easy despite having a 5 star rating.

Hope this helps out! Happy Hunting!