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"
Obtained Total LV 10,000
Defeated the Extra Boss "Marjoly"
Obtained Total LV 5,000
Defeated the Extra Boss "Priere"
Dealt 100,000 Damage!
Cleared Extra Stages "Cave of Ordeal"
Obtained 10,000,000 HL at the end of battle
Obtained Total LV 1,000
Defeated the Extra Boss "Item King"
Completed Final Episode "What Lies Beyond the Battle"
Performed your first transmigration
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"
Completed Ep. 1 "Prince of the Netherworld"
Killed 100 enemies!
Defeated the Extra Boss "Baal"
Defeated all EX bosses!
Defeated the Extra Boss "Item God"
Defeated the Extra Boss "Item God 2"
Dealt 10,000,000 Damage!
Performed 10 transmigrations
Obtained the Hyperdrive!