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