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