Here is the full list of all 20 Naked Puzzle: Girls achievements.
Don't click "X"!
Use skill 1000 times!
Use skill 100 times.
Not bad!
Finish all puzzles with May.
Ho ho, nice!
Cool! You saw all pantsu!
Finish all puzzles with Sakura.
Solve 3000 blocks!
Finish all puzzles with Yuri.
Solve 1000 blocks.
Finish all puzzles with Miki.
Solve 666 blocks.
Finish all puzzles with Saya.
Use skill 10 times.
Use ability for the first time.
Finish all puzzles with Megumi.
Solve 100 blocks.
Welcome brother.
Thanks!