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