Here is the full list of all 27 How to Sing to Open Your Heart achievements.
You've cleared Chapter 7★Teamwork!
You've cleared Chapter 6★Teamwork!
Nothing can suppress this feeling anymore.
You've cleared Chapter 5★Teamwork!
You've cleared Chapter 4★Teamwork!
You've cleared Chapter 3!
You've cleared Bonus★Teamwork 3!
You've cleared Chapter 2!
You've cleared Bonus★Teamwork 2!
You've cleared Chapter 1!
You've cleared Bonus★Teamwork 1!
You've cleared the Prologue!
You've cleared Bonus★Independent 1!
You've cleared Bonus★Independent 2!
You've cleared Bonus★Independent 3!
You've cleared Chapter 4★Independent!
You've cleared Chapter 5★Independent!
You've cleared Chapter 6★Independent!
You've cleared Chapter 7★Independent!
You've cleared Chapter 8★Independent!
You've got the Independent Route Ending!
You've got the Teamwork Route Ending!
You've cleared Chapter 8★Teamwork!
You've unlocked all of the Achievements!
You've unlocked all of the CGs.
You've unlocked all of the Music tracks.
We don't need words to express this feeling.