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