Ultrahard steel (Before the Fall Manga)

Chō Kōshitsu Suchīru (超硬質スチール) is a material that is used in the making of blades capable of cutting and piercing the skin of Titans.

Creation
The steel is created in the factories of production cities, where it is melted down and forged into the metal needed for the blades. The metal cannot be produced in any other place.

The blades were created by Angel Aaltonen, a first-class weapons craftsman who collaborated with the Survey Corps 50 years before the fall of Wall Maria. He was also the creator of the vertical maneuvering equipment.