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