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