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