Here is the full list of all 17 Hentai Girl Division achievements.
Kill 4000 enemy
Kill 100 elite enemy
Reach level 3 for atleast one girl
Reach level 5 for atleast one girl
Reach level 5 for all girl
Finish main story
Beat all challenge mission
Collect 5000 star
Talk with every girl when possible
Watch every hentai scene
Finish main story in Hardcore mode
Upgrade atleast one skill to max level
Upgrade to maximum fire rate for at least one girl