Here is the full list of all 20 the 9th day achievements.
accomplish all above and get a platinum trophy.
Game time breaks through 20 hours.
Occupy all archive places.
Another story pass.
Go through the whole game following the option order.
Collect all CG.
Game time breaks through 10 hours.
Pass Saki line again after passing Another story.
Mai line pass.
Saki line pass.
Suzu line pass.
Maki line pass.
Appreciation mode all music listen once.
Watch ED for the first time.
Through the link in game to arrive at the official shop.
Through the link in game to arrive at the official blog.
Through the link in game to arrive at the official website.
Watch OP for the first time.
Prologue finish.
Save the game once.