Here is the full list of all 20 If My Heart Had Wings achievements.
Complete the game for the first time.
Complete the Kotori route.
Watch the ending movie.
Watch 40% of the cutscenes.
Open the gallery.
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.
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 60% of the cutscenes.
Watch 80% of the cutscenes.
Watch all of the cutscenes.