Here is the full list of all 20 If My Heart Had Wings achievements.
Watch the first opening movie.
Watch a cutscene for the first time.
Start the game.
Open the gallery.
Watch the second opening movie.
Watch the ending movie.
Finish the common routes.
Complete the game for the first time.
Complete the Kotori route.
Complete the Amane route.
Complete the Ageha route.
Complete the Asa route.
Complete the Yoru route.
Fail to complete any route.
Complete all routes.
Watch 20% of the cutscenes.
Watch 40% of the cutscenes.
Watch 60% of the cutscenes.
Watch 80% of the cutscenes.
Watch all of the cutscenes.