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