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