Here is the full list of all 30 Arietta of Spirits achievements.
Complete the game on Extreme Mode.
Find all lost Spirit Cubs.
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.
Harvest all vegetables from the garden.
Complete the Journal.
Defeat the Roamer Behemoth.
Unlock the Large Roamer Core.
Ladders finally fixed.
Pick blueberries for Mom.
Defeat the Cloaked Roamer.
Unlock the Medium Roamer Core.
Find Gibb's workshop.
Unlock the Spirit Shield.
Unlock the Small Roamer Core.
Obtain the Herbicide.
Defeat the Spikeroot Roamer.
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.
Kill a butterfly.
Defeat the Wasp Queen.
Obtain the Wooden Sword.
Find Grandma's portrait.