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