Shusui

Shusui is 1 of 5 Supreme swords that was once wielded by the legendary God of Thunder Takemikazuchi. It is a prized national treasure of Yamagakure. After his death, the katana was buried with Takemikazuchi.
==Appearance==
Shusui is a black blade that has as distinct white reverse wave hamon (hardening line) that is of a Kanemoto style and its tsuba (handguard) has flower-like edges in the shape of an octofoil. It also has no accessories on the hilt, being wrapped with black silk. Kashira, tsuba and kojiri end cap are golden, and the sheath is black, decorated with dark red circles split into even thirds.
In descriptive terms, Shusui is a Hira Zukuri katana with a black blade. Shusui has a solid hilt with a samegawa wrapped around it. The kashira is identical to the kojiri found at the end of the sheath. The crossguard is in the shape of a flower, with the sides being dark gold but the edge is normal gold. There are two half-circle holes on each side of the blade. A saw hamon pattern adorns the sides of this blade in a shining dark magenta while the hamon of the blade is colored purple, though it is equally as dark as the black bo-hi. Shusui has a traditional sheath, but a pattern of circles in their thirds can be found stretching across it.
==History==
The sword originally belonged to Takemikazuchi, and was buried with him upon his death, where it was prized as a national treasure. It was said that Shusui was not always a "black blade", and it became one after many battles alongside its master.
1300 years ago the sword was stolen but has since been found and returned.
==Trivia==
*Shusui’s Connection to Storms: Some believe that Shusui might be linked to the ability to summon storms or manipulate thunder. The fact that Takemikazuchi is a Thunder God suggests that the sword could have been an amplifier of divine powers, and it’s possible that whoever wielded it had control over weather conditions or could summon lightning in battle.
*Cursed Blade Theory: Given its long history of violence and its transformation into a black blade, some believe that Shusui may carry a curse. This curse could manifest as the blade slowly consuming the soul of its wielder over time or making them crave more battle, much like a weapon that grows more powerful the more blood it spills. The sword’s theft and return might also signify the sword’s restless nature, always drawn to conflict.
* Shusui as a Soul-Tethering Sword: A popular theory is that the sword can bond with the soul of its wielder, growing stronger with each battle. This could explain why Shusui became a black blade over time—because it absorbed the energy and souls of those it killed. This would also make the blade highly selective about its masters, choosing those with the potential to unleash its true power.
* Takemikazuchi’s Immortality: Some believe that Takemikazuchi never truly died, and his spirit continues to reside within Shusui. The sword might be a vessel for his godly essence, and whoever wields it may unknowingly be hosting the Thunder God’s power. This would explain why the blade is so heavily associated with thunder and lightning, and why it may have the ability to enhance its wielder's abilities.