Here is the full list of all 42 White Day: A Labyrinth Named School achievements.
You Are Mine
Hidden Love
You Can't Do this
Clear Hell Mode
Each Encounter is a Surprise
Forgive Me
Friendship
Truth
Experience Death 10 Times
Arrive at the Bottomless Pit
Visit the Labyrinth
Encounter All the Ghosts in Yeondu High School
Complete the Ghost Collection
Woman living in a cabinet
Bathroom is Scary
Tired of Love
Sincerity
Dangerous Pleasure
Collect All the Ghost Stories of Yeondu High School
Hipocrisy
Clear Hard Mode
Arrive at the Auditorium
Experience Death for the First Time
I'm Perfectly Fine
Arrive at the New Building
Delicious Soy Milk
Arrive at Main Building 2
Head Ghost Has Nice Hair
Enter Main Building 1
Experience Death 50 Times
Experience Death 100 Times
Clear Very Easy Mode
Clear Easy Mode
Clear Normal Mode
Clear Hell Mode 7 Times
Clear Hell Mode 10 Times
Complete the Ending Collection
Flirt with the Girls
She Approaches from Afar
The Scent of the Bathroom is Becoming Heavenly
Hee-min, Still a Growing Boy?
Nothing Fazes Me Now