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