Here is the full list of all 48 Infinite Mana achievements.
Unlock the Warden Guise.
Unlock the Trickster Guise.
Unlock the Disciple Guise.
Unlock the Conjurer Guise.
Unlock the Soul Thief Guise.
Unlock the Spellblade Guise.
Unlock the Ranger Guise.
Unlock the Rhythmancer Guise.
Unlock the Reanimator Guise.
Unlock the Songhammer Guise.
Unlock the Illustromancer Guise.
Unlock the Privateer Guise.
Unlock the Tarotist Guise.
Unlock the Tamer Guise.
Unlock the Machinist Guise.
Complete the Prologue.
Complete Chapter 1-2: Memories.
Complete Chapter 3: Dear Friends.
Complete Chapter 4: Far Off Places.
Complete Chapter 5: The Fall.
Complete Chapter 6: The Sands Of Fate.
Complete Chapter 7: City Of Secrets.
Complete Chapter 8: No Man's Sea.
Complete Chapter 9: Old Wounds.
Complete Chapter 10: The Ascent.
Complete Chapter 11: The Origin.
Complete the Doll Swap quest.
Obtain all Collectibles.
Obtain all seashells.
Pet all pettable creatures.
Collect all the fish.
Read all the books.
Pray to all Empyrean statues.
Dig up all archaeological artifacts.
Collect every Relic.
Gain the power of Infinite Mana.
Unlock the power of all Guardian Founts.
Join the Rogue's Guild.
Close the rift outside of Densetsu Village.
Complete every Hunt for the Hunter's Guild.
Buy the Homestead in Densetsu Village.
Become the Lord of the Monsters.
Obtain the ship.
Obtain the airship.