Here is the full list of all 24 Super Turbo Demon Busters! achievements.
Kill 20,000 monsters
Kill 10,000 enemies
Complete 100 quests
Kill 5000 monsters
Unlock all mercenaries
Kill 250 monsters with a machine gun
Kill 2500 monsters
Level up a mercenary 20 times
Kill 250 zombies
Kill 1000 enemies
Complete 50 raids
Earn 50,000 credits
Kill an enemy while your health is at 1%
Kill three enemies with a shotgun round
Kill 100 ghosts
Level up a mercenary once
Have 10 guns in your arsenal
Break 50 crates
Search 150 corpses
Earn 5000 credits
Kill 25 monsters
Complete your first quest
Complete your first raid
Kill your first monster