Here is the full list of all 37 Ark Mobius achievements.
Playing Ark Mobius for the first time
Complete the first rhythm battle
Complete Sylph's rhythm battle 1
Complete Sylph's rhythm battle 2
Complete Sylph's rhythm battle 3
Complete Ruri's rhythm battle 1
Complete Ruri's rhythm battle 2
Complete Ruri's rhythm battle 3
Complete Neferura's rhythm battle 1
Complete Neferura's rhythm battle 2
Complete Neferura's rhythm battle 3
Complete all Chiyuki's rhythmic battles
Unlock all music collections
Defeat the black goat
Reach the [Chiyuki : alive] ending
Reach the [Broken world] ending
Reach the [Sylph : accompany] ending
Reach the [Sylph : pass by] ending
Reach the [Sylph : tragedy] ending
Reach the [Eleanor : accompany] ending
Reach the [Eleanor : pass by] ending
Reach the [Eleanor : tragedy] ending
Reach the [Ruri : accompany] ending
Reach the [Ruri : pass by] ending
Reach the [Ruri : tragedy] ending
Reach the [Neferura : accompany] ending
Reach the [Neferura : pass by] ending
Reach the [Neferura : tragedy] ending
Chiyuki's favorability reached 999
Unlock all Chiyuki's items in gallery
Unlock all Sylph's items in gallery
Unlock all Eleanor's items in gallery
Unlock all Ruri's items in gallery
Unlock all Neferura's items in gallery
Complete Eleanor's rhythm battle 1
Complete Eleanor's rhythm battle 2
Complete Eleanor's rhythm battle 3