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