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