Here is the full list of all 33 SoulSet achievements.
Read the whole thing!
Unlocked The Secret Ending
Unlocked Marco's True Ending
Unlocked Feathor's True Ending
Unlocked Mariko's True Ending
Found all the Red Clues
Unlocked Feathor's Normal Ending
Unlocked Feathor's Bad Ending A
Found all the Green Clues
Unlocked Marco's Bad Ending A
Unlocked Shirr's True Ending
Unlocked Shirr's Normal Ending
Found all the Silver Clues
Unlocked Shirr's Bad Ending B
Unlocked Shirr's Bad Ending A
Unlocked Verin's True Ending
Unlocked Verin's Normal Ending
Unlocked Verin's Bad Ending A
Unlocked Apris' True Ending
Unlocked Apris' Normal Ending
Unlocked Apris' Bad Ending C
Unlocked Apris' Bad Ending B
Unlocked Apris' Bad Ending A
Unlocked Shira's True Ending
Unlocked Shira's Normal Ending
Found all the Orange Clues
Unlocked Shira's Bad Ending B
Unlocked Shira's Bad Ending A
Unlocked Yvonne's True Ending
Unlocked Yvonne's Normal Ending
Unlocked Yvonne's Bad Ending A
Was he in there all along?
Choose wisely, My Liege