The ouroboros -twin stroke of the end- Add-on for Groove Coaster has 6 achievements.
Play ouroboros -twin stroke of the end- 20 times
Play ouroboros -twin stroke of the end- and clear all of SIMPLE, NORMAL and HARD
Play ouroboros -twin stroke of the end- and get A Rank in SIMPLE, NORMAL and HARD
Play ouroboros -twin stroke of the end- and get S Rank in SIMPLE, NORMAL and HARD
Play ouroboros -twin stroke of the end- and get S+ Rank in SIMPLE, NORMAL and HARD
Play ouroboros -twin stroke of the end- and get S++ Rank in SIMPLE, NORMAL and HARD