Touken Ranbu: The Swordsmith’s Tsukumogami

Swords and blades have jade steel for their bones, their bodies forged in charcoal fires.

Those known as Saniwa awaken the spirits of the objects sleeping within them.

"I don't have any jade steel. Want to try stainless steel? I've got some with an HRC of 65+, and it can be heat-treated to form martensite."

Fox-with-Socks was so distraught at meeting a Saniwa like this for the first time that it started shedding fur.

"You can't do that, my lord Saniwa! You have to use jade steel to forge swords!"

The Saniwa from the modern world looked utterly desperate.