Here is the full list of all 30 Disgaea PC achievements.
Dealt 10,000,000 Damage!
Completed Final Episode of Etna Mode "Chronicles of Etnarnia"
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"
Obtained Total LV 10,000
Defeated the Extra Boss "Marjoly"
Dealt 100,000 Damage!
Defeated the Extra Boss "Priere"
Defeated the Extra Boss "Item King"
Cleared Extra Stages "Cave of Ordeal"
Obtained 10,000,000 HL at the end of battle
Obtained Total LV 5,000
Obtained Total LV 1,000
Obtained Total LV 100
Obtained 1,000,000 HL
Obtained the Dream Hand!
Completed Ep. 10 "Angels, Demons, and Humans"
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"