Find and open the lewd book in Level 1 - Room 7.
Find and open the lewd book in Level 1 - Room 8.
Find and open the lewd book in Level 1 - Room 11.
Defeat the first Boss and open the lewd book in Level 1 - Room 14.
Find and open the lewd book in Level 2 - Room 7.
Find and open the lewd book in Level 2 - Room 8.
Find and open the lewd book in Level 2 - Room 12.
Defeat the second Boss and open the lewd book in Level 2 - Room 15.
Find and open the lewd book in Level 3 - Room 7.
Find and open the lewd book in Level 3 - Room 9.
Defeat the final Boss and open the lewd book in Level 3 - Room 15.
Complete the game and open the lewd book in the final scene of the game.