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