Here is the full list of all 15 Girls! Girls! Girls!? achievements.
You have been a very good boy!
You have turned the tables, woah!
You reached your first date with Sena, congrats!
You reached your first date with Ayase, congrats!
You reached your first date with Hayasaka, congrats!
It's impressive you have managed to do that!
Thank you for trying, but it's really over.
What you did will be remembered for ages.
You have reached your the harem ending, congrats!
You have reached the bad ending.
You have reached the best ending ever.
Awarded for reaching 100% Completion of Girls! Girls! Girls!?