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