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