Here is the full list of all 30 Arietta of Spirits achievements.
Find all lost Spirit Cubs.
Harvest all vegetables from the garden.
Kill a butterfly.
Complete the game on Extreme Mode.
Complete the game.
Escape from the Sunken Realm.
Defeat the Sunken Behemoth.
Help Minerva cross over to the afterlife.
Find all of Midri's goods.
Complete the Journal.
Defeat the Roamer Behemoth.
Unlock the Large Roamer Core.
Ladders finally fixed.
Unlock the Medium Roamer Core.
Pick blueberries for Mom.
Defeat the Cloaked Roamer.
Find Gibb's workshop.
Unlock the Spirit Shield.
Obtain the Herbicide.
Defeat the Spikeroot Roamer.
Unlock the Small Roamer Core.
Find Minerva's hut.
Help out Father in a sticky situation.
Find Grandma's portrait.
Get to keep Grandma's Silver Ring.
Defeat the Huge Roamer.
Obtain the Spirit Sword.
Become a Bound.
Defeat the Wasp Queen.
Obtain the Wooden Sword.