Here is the full list of all 28 Lovely Island achievements.
Peep for the first time.
Visit the uninhabited island.
For the first time to meet Sophie.
Create a romantic atmosphere.
Fanservice is our everything.
Steal the panties.
Turn on the fan.
Win the quiz.
Stay alone.
Get on campus.
Finish Alice's route.
Finish twins' route.
Finish Sophie's route.
Visit the arcade.
Visit the lighthouse.
Visit the beach.
Visit all locations of the island.
Name the protagonist.
Talk to Android.
Hide in the closet.
Take some pictures.
Save Ai.
Attend a beach party.
Launch fireworks.