Here is the full list of all 10 Project Kat - Paper Lily Prologue achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Reached the true ending.
Completed the ritual successfully.
Found the letter in the theater club room.
Read the full ritual rules.
Recruit the 3 girls into your party.
Picked a lock.
Reached the wrong ending.
What else is this used for?
You've done the opposite of what I expected.
You should be more careful about the decisions you make.