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