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