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