Mekki is the eleventh Deviant Blade that Togame and Shichika Yasuri obtained on their journey. It was wielded by Kiki Shikizaki, while possessing the body of Hōō Maniwa, then later wielded by the Shogun's retainer, Bangai Rogiri.
Mekki is the most poisonous blade of all, in the Deviant Blade series. It is a very ominous blade that exhausts viridescent smoke with iridescent designs. Unlike Japanese swords, it is a jagged blade with an inscription on the side of the blade.
Hari's main strength is its doses of deadly poison and power to preserve ones memory. Since it's a sword created by Shikizaki importing future records (as in Shikizaki's soul enters the users body), it is extremely unstable for one to wield without knowing how they are eventually driven insane by the sword's poison. Like other deviant blades, the sword can surpass the laws of physics, however, Mekki is powerful enough to eradicate buildings with a single swing, it also emits particles that kill living things. Maniwa village was hence annihilated by it.
When Emonzaemon fought Hōō, he lost right after Hōō went berserk when Shikizaki's spirit entered Hōō's body from the sword itself. Then, Hōō (Shikizaki) manages to strike him down but Emonzaemon survived. This shows that Mekki also boosts one's physical ability.
When Pengin was attacked by Hōō in his berserk state, he survived too, this could be due to his Ninpō.
Mekki could mean "gilt", "Plating", "pretence", "pretense".