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