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