Able to possess and sap the power of its wielder, or if channelled correctly, provide immense strength and power at the cost of the wielder’s soul, legends kept by the Shinmeiryu posit that the sword was once wielded by Akechi Mitsuhide, suggesting that he was once a practitioner of the style. The legend states that when Akechi, no longer able to tolerate the injustices of his master, Oda Nobunaga, rose in rebellion and forced Oda's death at the Incident at Honnō-ji, the evil spirit of Oda possessed Akechi and drove him to insanity, resulting in the popular description of the battle as "drowning Kyoto in a sea of flame." The entire existing force of Shinmeiryu based in Kyoto at the time arrived to battle Akechi in an attempt to exorcise the evil spirit. The resultant battle resulted in the deaths of nearly every participant in the battle, but ultimately Akechi was subdued and the cursed blade sealed.
While this has been recorded as a legend of the dojo, what is known is that the blade ended up as a family heirloom for the Urashima family, who presumably guarded it. The sword was presented to Motoko Aoyama as a replacement blade for her Shisui katana. However, Motoko sensed the evil that the sword emanated and refused to wield it. Instead Naru was possessed when she drew the blade to help Motoko in a battle against her sister, Tsuruko Aoyama. Fortunately the blade was sealed by Motoko before it could do much damage.
Although it was sealed, it only meant that Motoko could wield it without the danger of being possessed while other wielders, such as Tama and a hot springs monkey, were still in danger of being consumed.
- Kuro Arashi: The Black Storm (First appearance)