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.
Find the message in the back of the laboratory.
Read the diary in the library.
Clear Truth with the female protagonist.
Free Kurata in the Truth route.
Give Misao some coins
See the bad ending.
Clear the main game with the female protagonist
Play the piano.
Refuse to help Yoshino.
Hide in a cardboard box.
Talk with Library multiple times.
Jump off the rooftop.
Read "The Lazy-Eyed Ranger."
Encounter Hanako.
Save Kudoh.
Check your key items.
Have a meal.
Get a whiff of a toilet.
Make a quicksave.