Operation Babel: New Tokyo Legacy

You need to acquire the item Murasama H, a level 80 item. Unlike in Operation Abyss, you can't use gamble codes for this. This is a possible drop in Lethal Hall or in the Embryo Arc. I acquired this myself in the Lethal Hall. The item has to be identified in order to earn this. The Lethal Hall tends to drop better quality items, but at the expense of much fewer fights.