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