Originally identified by Nova as carrying the most precious thing on Earth, it is a mysterious container that Alita carries while infiltrating Melchizedek’s core.
It contains just a living brain without a body.
The revelation of its provenance will shock the trespassers.
[Initially seen in Last Order, volume 1, Angel Reborn, page 163; the Viz__ editions refer to it as an "F-Box," so that it still makes sense when Alita guesses that the box has "flan" in it. (The Japanese word for "flan" is "purin.")]