Here is the full list of all 18 Hentai Zodiac Puzzle 2 achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Unlock all achievements
Open the twelfth girl
Open the eleventh girl
Open the tenth girl
Open the ninth girl
Open the eighth girl
Open the seventh girl
Open the sixth girl
Open the fifth girl
Open the fourth girl
Open the third girl
Use random choice
Open the second girl
Use hint
Open the first girl
Don't use hints
Click on a wrong spot
Find the first difference