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