Here is the full list of all 20 Viola achievements.
Viola retains the connection to Vylna, forging her own path.
Viola returns home, destroying the world of Vylna.
Viola remains in Vylna, never returning home.
Reach Support Level S with Emerald.
Reach Support Level S with Mallow.
Reach Support Level S with Ceryn.
Reach Support Level S with Arti.
Reach Support Level S with Justice.
Complete every Personal Quest.
Recruit all 10 characters.
Reach Support Level S with Momo.
Learn all nine songs.
Reach Support Level S with Fenrys.
Reach Support Level S with Niko.
Reach Support Level S with Soleil.
Reach Support Level S with Sybil.
Recruit a full party.
Buy something in the Catshop.
Learn Viola's first song.
Beat the first level.