Here is the full list of all 21 planetarian HD achievements.
Used the Music Mode
Completed planetarian ~the reverie of a little planet~
Used the CG Mode
Finished Chapter 16, "Yumemi's Prayer"
Finished Chapter 15, "A Holographic Reflection"
Finished Chapter 14, "At the End of the Battle"
Finished Chapter 13, "The Battle Against the Fiddler Crab"
Finished Chapter 12, "At the Rift in the Quarantine Wall"
Finished Chapter 10, "The City 1 (The Abandoned Streets)"
Finished Chapter 11, "The City 2 (Drunk with Alcohol and Rain)"
Finished Chapter 9, "Leaving the Planetarium Behind"
Finished Chapter 8, "The Reverie of Mankind Spreading its Wings"
Finished Chapter 6, "The End of Repairs / Before the Projection"
Finished Chapter 7, "Yumemi's Projection"
Finished Chapter 5, "The Junker's Reverie 2 / Light Bulbs"
Finished Chapter 4, "Repairing the Projector"
Finished Chapter 3, "The Junker's Reverie 1 / At Reception"
Finished Chapter 2, "The Sealed City and the Junker"
Finished Chapter 1, "The Robot's Bouquet"
Read the Opening
Started planetarian for the first time