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