Here is the full list of all 21 Misao: Definitive Edition achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Clear Truth with the male protagonist.
Clear the main game with the male protagonist.
Clear Truth with the female protagonist.
Check your key items.
Talk with Library multiple times.
See the bad ending.
Give Misao some coins
Find the message in the back of the laboratory.
Clear the main game with the female protagonist
Free Kurata in the Truth route.
Refuse to help Yoshino.
Read the diary in the library.
Play the piano.
Save Kudoh.
Hide in a cardboard box.
Jump off the rooftop.
Have a meal.
Encounter Hanako.
Get a whiff of a toilet.
Read "The Lazy-Eyed Ranger."
Make a quicksave.