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