Here is the full list of all 15 Oppaidius Summer Trouble achievements.
Congratulations! You unlocked every art in the game!
Discovered the secret of the yellow dinosaur in Bermuda shorts.
Got every ending!
Waited for 2 minutes at the right moment…
Got ending “A”.
Reached the “Hot Secret Scene”!
Achieved a “Max Combo” hit count in the massage minigame!
Set “boobage level” to 100.
Won the swimming race.
Made Serafina’s breasts bounce through the power of your mind.
Went to the arcade with Serafina.
You didn’t miss them, did you…?
Discovered your spirit animal.
Lost the swimming race.
Started the game for the first time.