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