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