Here is the full list of all 20 Saint Gear Force achievements.
Finish Prologue
Clear Chapter 1
Clear Chapter 2
Clear Chapter 3
Clear all scenario
Defeat 1000 enemies
Obtain Jamming Device
Become submissive
Become a hardcore masochist
Defeated by Abductor
Defeated by Head Researcher
Defeated by Tentacle Creature
Defeated by Lady Manager
Defeated by Secret Organization Chairman
Reach breast sensitivity Lv5
Reach vaginal dilation Lv5
Complete skill tree
Clear the game as a virgin
Lose virginity
Reach both vaginal dilation Lv5 and breast sensitivity Lv5