Operation Babel: New Tokyo Legacy

To earn this, you need to acquire the following:

Valk Lance (level 14)
Valk Lance 2 (level 37)
Last Valk (level 78)

You can acquire the Valk Lance and Valk Lance 2 through Gamble Code. Valk Lance can also be bought from the Development Lab. The Last Valk can only be acquire through treasures in either the Embryo Arc or Lethal Hall. The Lethal Hall tends to drop higher quality items. It's not necessary to have all of these in your possession at once. To check what you're missing, go to CPA Headquarters, Information Terminal, Activity History, and then Item.