Here is the full list of all 21 Beautiful Mystic Defenders achievements.
Defeated monster commander Blightwing.
Defeated monster commander Gnash.
Defeated monster commander Venomghoul.
Defeated monster commander Grimsbane.
Defeated monster commander Grimm.
Defeated monster king Moldark.
Level up Kitsune to 5.
Level up Yasako to 5.
Level up Airi to 5.
Level up Sumi to 5.
In love with Takami.
Achieved 30 bronze stars in total.
Achieved 60 bronze stars in total.
Achieved 90 bronze stars in total.
Achieved 30 silver stars in total.
Achieved 60 silver stars in total.
Achieved 90 silver stars in total.
Achieved 30 gold stars in total.
Achieved 60 gold stars in total.
Achieved 90 gold stars in total.
Purchased all upgrades.