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