Here is the full list of all 16 Black Closet achievements.
You have kissed (or been kissed by) a freshman.
Unlock All CGs in both art sets
Win the final conflict with three minions on the Student Council
You have used a minion as your own personal slave.
Win the final conflict with only two minions left on the Student Council
One of your minions has gotten a little too possessive.
Win the final conflict with four minions on the Student Council
The seats recline so that you can look at the stars....
As long as you're both adults...
You have graduated from St. Claudine's.
She's straight, but not rigid.
You have been fully initiated into the Red Mask Society.
You infiltrated the Red Mask Society in order to betray them
Your Queen has been poisoned by the Red Mask Society. Must have been those chocolates.
You have run a lemonade stand.
You have managed to win a traitorous minion back to your side.