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