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