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