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