Here is the full list of all 42 White Day: A Labyrinth Named School achievements.
You Are Mine
Clear Very Easy Mode
Hidden Love
Forgive Me
Clear Hard Mode
Friendship
Arrive at the Bottomless Pit
I'm Perfectly Fine
Visit the Labyrinth
Arrive at the Auditorium
Experience Death 10 Times
Arrive at the New Building
Arrive at Main Building 2
Each Encounter is a Surprise
Head Ghost Has Nice Hair
Experience Death for the First Time
Woman living in a cabinet
Bathroom is Scary
Delicious Soy Milk
Enter Main Building 1
Experience Death 50 Times
Experience Death 100 Times
Clear Easy Mode
Clear Normal Mode
Clear Hell Mode
Clear Hell Mode 7 Times
Clear Hell Mode 10 Times
Truth
Dangerous Pleasure
Hipocrisy
Sincerity
Tired of Love
Encounter All the Ghosts in Yeondu High School
Collect All the Ghost Stories of Yeondu High School
Complete the Ghost Collection
Complete the Ending Collection
You Can't Do this
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