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