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