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