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