Here is the full list of all 16 School For The Friendless achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Make Scout fall for you.
Get Guy as your roommate.
Get Anima's worst ending.
Be best friends with Anima at the end.
Make Anima fall for you.
Get Anima as your roommate.
Get Vivian's worst ending.
Be best friends with Vivian at the end.
Punched Vivian's brother.
Make Vivian fall for you.
Get Vivian as your roommate.
Get Scout's worst ending.
Be best friends with Scout at the end.
Went with Scout to the basement.
Get Scout as your roommate.
Get involved with the girls drawing on the board.