Here is the full list of all 41 SG/ZH: School Girl/Zombie Hunter achievements.
Clear a Boss mission for the first time.
Defeat a total of 5,000 enemies.
Obtain shoes for the first time.
Obtain 50% of all weapons.
Clear Chapter 2.
Defeat a total of 1,000 enemies.
Clear a Timed Survival mission for the first time.
Clear a Fetch mission for the first time.
Clear Chapter 1.
Defeat all Charons in one mission, then clear the mission.
Use Mayaya for the first time and clear a mission.
Use a Club Attack 10 times in a single mission.
Use a Club Attack for the first time.
Undress for the first time.
Use Rei for the first time and clear a mission.
Defeat a total of 100 enemies.
Use Enami for the first time and clear a mission.
Obtain a new weapon for the first time.
Use Risa for the first time and clear a mission.
Obtain an oufit for the first time.
Clear a Destination mission for the first time.
Defeat Charon for the first time and then clear a mission.
Use Sayuri for the first time and clear a mission.
Clear a mission for the first time.
Attack a zombie's weak point for the first time.
You achieved everything!
Defeat a total of 10,000 enemies.
Obtain all weapons.
See the ending by beating the game.
Obtain Rank SSS in all offline missions on all difficulty settings.
Defeat all Charons and then clear any mission.
Obtain all oufits.
Obtain all shoes.
Clear all offline missions on all difficulty settings.
Clear Chapter 3.
Clear Chapter 4.
Clear Chapter 5.
Use an Underwear Trap for the first time.
Undress 3 people during a single mission.
Defeat Ren by yourself in an offline mission or hosted online mission.
Defeat Die Jaeger by yourself in an offline mission or hosted online mission.