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