Hit any key and difficulty of a song 100 times. After that, you only need to hit other keys and difficulties of the song again to get another one, so you can get 9 points for a song.

The last medal for a dear performer is to play any song 100 times

Playing a song with any number of keys and difficulty a hundred times will get one. Restarting the song before it is finished will also be counted.

Oh oh~, I got it, thank you for clarifying my doubts.