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