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