Here is the full list of all 35 HENTAI PUZZLE achievements.
Couchtime
Start a new game with progress of a least 5 completed puzzles
Click the hint button 30 times
Click a tiny dick 10000 times
Click a tiny dick 9001 times
Click a tiny dick 5000 times
Click a tiny dick 1000 times
Click a tiny dick 500 times
Click a tiny dick 200 times
Click a tiny dick 100 times
Click a tiny dick 50 times
Click a tiny dick 10 times
Click a tiny dick 20 times
Click a tiny dick 5 times
You noticed you have a small dick to play with
Skip the story dialogs 200 times
Turn off the In-Game Music
Click *yourself* back to the menu
Complete the game
Sticky Eggplant
What a mouthful
Hands On
Get over here
Slowly pressed against the glass
Sushi???
Pressed against the glass
Complete 5 Puzzles
Complete the cow puzzle
Complete the second second puzzle
Complete the second puzzle
Skip the story dialogues 20 times
Clicked the next puzzle button in the first stage
Complete a puzzle without using the hint button
Complete the first puzzle
Skip the Introduction story