Here is the full list of all 30 Disgaea PC achievements.
Obtained the Hyperdrive!
Defeated all EX bosses!
Dealt 10,000,000 Damage!
Defeated the Extra Boss "Item God 2"
Performed 10 transmigrations
Defeated the Extra Boss "Baal"
Defeated the Extra Boss "Marjoly"
Obtained Total LV 10,000
Defeated the Extra Boss "Priere"
Obtained Total LV 1,000
Obtained 10,000,000 HL at the end of battle
Obtained Total LV 5,000
Cleared Extra Stages "Cave of Ordeal"
Dealt 100,000 Damage!
Completed Final Episode of Etna Mode "Chronicles of Etnarnia"
Defeated the Extra Boss "Item God"
Obtained Total LV 100
Defeated the Extra Boss "Item King"
Completed Ep. 1 of Etna Mode "Super Dimensional Etna"
Completed Final Episode "What Lies Beyond the Battle"
Obtained 1,000,000 HL
Completed Ep. 10 "Angels, Demons, and Humans"
Obtained the Dream Hand!
Performed your first transmigration
Killed 1,000 enemies!
Completed Ep. 5 "Etna's Secret"
Killed 500 enemies!
Defeated the Extra Boss "Item General"
Killed 100 enemies!
Completed Ep. 1 "Prince of the Netherworld"