Tamahagane

Special metal used only in sword crafting.

Tamahagane literally means "soul steel". There are only 10 available per play through.

Found[]

Chests

1 behind a breakable wall, along the east wall of the 2nd room of the Ancient Mausoleum. (Requires Fire Soul)

1 behind a breakable wall, in the 2nd room of the Western Skyway. (Requires Fire Soul)

1 in the Guardian Temple behind a puzzle door in the 4th room (Room before the Save room). Chests are easier to access with the Double Jump skill.
1 in the Guardian Temple, inside the room requiring a Demon Key to access. (Access door using Void Soul or Double Jump)

1 above the eastern entrance to Ishk . (Easier with Double Jump skill)
1 in Tagrum District, see Abyssal City Map
1 in the Ziggurat, in the same room as the Deadman's Fury . (Requires Void Soul [may substitute Double Jump skill and Seraphic Blades as Wyatt])
1 in the save room of the Tainted Laboratory. Access by entering the area from the Abandoned Gardens. (Requires Demon Key)
1 in the Abandoned Gardens, in the 3rd room (the first large room). Behind a timed door which requires a stomp switch to open.
1 in the Sunken Prison, in the room before the entrance to the Sanctuary. The chest is beneath the platform with the green enemies.