Here is the full list of all 12 Always The Same Blue Sky... achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Endear yourself to Kira as much as possible
Reach ending 1
Alienate yourself from Kira as much as possible
Reach ending 2
Demonstrate a firm scientific grasp
Visit the ancient courtyard
Try 2 different milkshakes
Take note of your surroundings
Captivated by what could be...
A calming glow
A burning fire
Travel to an undiscovered land