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