Here is the full list of all 18 Oppaidius Desert Island! achievements.
You began the adventure!
You set the “boobage level” to 100!
You won a beach volley match!
You won a swimming race earning something “spicy”!
The one most loved by kids and adults makes a comeback!
It could have been better… You have to retry, amazing adventures await you!
You unlocked the Rika Ending!
You unlocked the Angela Ending!
You unlocked the Dan-dan Ending!
“I never leave my TRAVEL BRACE behind…!”
You recommended all the greatest masterpieces to Dan-dan!
You made the breasts move with the power of your keyb-ehm, mind!
You have unlocked every special audio track!
You witnessed an incredible event that will pass into the annals of history…
Congratulations! You unlocked every beach volley minigame icon!
The Ultimate Summon was cast during a beach volley match!
You unlocked every art in the game!
We had to have this achievement, otherwise no one would have seen the special art…