Here is the full list of all 31 Fatal Twelve achievements.
Open Summary Mode
Open Scene Replay Mode
Open Gallery Mode
Get bad ending 4
View a story about a certain encounter
Get ending 2
Get ending 3
Get ending 1
Twelfth week's election concludes
Eleventh week's election concludes
Tenth week's election concludes
Ninth week's election concludes
Eighth week's election concludes
Seventh week's election concludes
Sixth week's election concludes
Fifth week's election concludes
Fourth week's election concludes
Start the game 12 times
Third week's election concludes
Second week's election concludes
First week's election concludes
Open Card Book Mode
Start the game
Get bad ending 1
Get bad ending 2
Get bad ending 3
Get all endings
Get all CGs
Select every choice at least once.
Switch languages
Reply to the confession