AA a song on heavy as your last stage.

EXTRA STAGE To unlock this song, you must clear a HEAVY chart with a rating of AA or higher on your FINAL STAGE. Notably, unlike in the arcade version or the Japanese CS version, a AA in this game can be achieved either through Dance Points or simply a FULL COMBO regardless of Dance Points. MAX 300's HEAVY chart (Single or Double depending on current play mode) will then become available as your EXTRA STAGE, with no way to change difficulty or song. The EXTRA STAGE is on a Pressure life meter; it starts out at maximum health, but will not be replenished. In addition, the x1.5 and Reverse modifiers are in effect, and the score counter is replaced by a timer displaying elapsed time.