Here is the full list of all 17 Open At Nine achievements.
Reach max level on all Monster Girls
Reach max lust rank on all Monster Girls
Finish all the H-events
Earn a total of 80000 coins
Reach the End Credits
Build all types of rooms at least once
Sign contracts with all the Monster Girls
Get Abel IX's balls empty
Failed to repay your debt
Use Revival Herb for a total of 10 times
Use Refusal Voucher for a total of 10 times
Use potion items for a total of 50 times
Sign contracts with Oriana and Kamaria
Build all 6 rooms (any type)
Add a room for the first time
Sign a contract for the first time
Open your business for the first time