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