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