Mashogane

Mashogane (魔性鋼, lit. "Devilish Steel"), also as "Jewel of Hokushin" (北見の宝石, Kitami no Hōseki) — rumored to have been named after the very being who forged it, is an evil artifact that's classified as one of the legendary Mysteria Relics — tools of immense power derived from origins beyond comprehension. Its existence has caused much disorder and has nearly destroyed various civilizations over the centuries, so much so that the Amahagane — its "good" counterpart, was created specifically to combat its negative influences.

Often classified as the element of Yin (陰, In), it's said to inflict misfortune on its enemies and amplifies the darkness in the bearer's soul — granting them incredible power in exchange for their sanity; this is most evident when exploited by a Demon, their already immeasurable power amplified to unfathomable degrees, making them more powerful than the most skilled of warriors. It's said that only users of the Amahagane are capable of standing up to, and subsequentially defeating an evil force as per the jewel's initial purpose.

Unlike the Amahagane, which is created through the Taiki Bansei (大器晩成, lit. "Late Maturity of Grand Talents") ritual, Mashogane are naturally grown and cultivated like Lacrima, found within the deepest darkest recesses of various planes of existence — the most notable being Megiddo. Interestingly enough, it's formed through the combination of evil souls, Magical Barrier Particles, and ample amounts of negative energy produced by divinities; this gives it the epithet, "Black-Stained Gem of the Eternal Darkness" (常闇の寳墨染め, Tokoyami no Houmitsu Sumizome).

Overview
"Never has there been an item that embodies the concept of negativity like the Mashogane. It's the pinnacle of all sin, given life in the form of a crystal. Those that harness its malevolent powers are said to be individuals who gave into their dark desires, foregoing their humanity to achieve greater heights. Born from darkness, enhances the darkness, and fades into darkness, it's the only relic that's considered to be a threat to all stability in creation."

- An Esoterologist's brief explanation of the Mashogane via his research and findings.



Heishimei
"Manifestations of the Mashogane's will, embodiments of their negative desires. It's said that these warriors are the defenders of the crystal, protecting it from all harm. At the same time, they destroy anything and everything that said crystal desires — leaving none spared from its wickedness. Even its users will succumb to its powers and be enslaved as one of its henchmen should the chance arise. Truly, the crystal itself can be considered the most powerful of Demons — only subdued by the Amahagane's power."

- Jin Asakura on the Heishimei's nature.

The Heishimei (斃死冥, lit. "Perishing Underworld") are....

Trivia

 * The name of this article was chosen by a randomizer for Japanese weaponry and objects because the author couldn't come up with something proper.
 * This is one of the two ideas the author was kicking around during his "hiatus" from the wikia. He decided to go with it anyways because of the ideas he had for his other article, Amahagane, which he wanted to use to explore more of the Heroic Chronicles universe and expand on two certain characters; also, the idea for this article came from the Magic Stones that's seen in various media, but in this case, wanted to make it look more "sinister", thus serving as an antipode to the aforementioned, thus boosting its importance. So, in a sense, this article is also a plot device, playing a vital role in one of the storylines the author has planned out in the near future.