Obororyu Kenjutsu(朧流剣術 Oboro Style Swordsmanship) or simply the Oboro Style, is a form of swordsmanship created by Oboroya Senju. Known for its ferocity and lethality in its mastery over all manner of supernatural swords, it is a powerful way of dark combat feared by many. The style makes use of Muramasa blades with efficiency and deadliness. Those who know how to unleash the Secret Arts of Muramasa Blades are immune to the effect of insanity. Those who wield Muramasa blades without mastery of Secret Arts will fall to blood lust and violent desires.
Long ago, Oboroya Senju crafted the style using swordsmanship and supernatural arts taught to him by Mumyo Daoshi, a master of sorcery. With his knowledge, he developed a form of lethal combat that enabled the user to completely control any and all supernatural blades with inhuman ease. He would dub his art Oboro Style.
In his advanced age, Senju would take on many students, one in particular, was Izuna Junkuro. However, Jinkuro, in his greed attempted to become the sole master of the style, wanting the overwhelming power of the Oboro style for his own. He viciously slaughtered his fellow students and murdered Senju. However, this would not be the end of the style, for Senju, wandering in limbo, came across the spirit of the Iga ninja Kisuke. As Kisuke was betrayed by the Skull Valley Ninja, Senju offered him life in exchange of carrying on his powerful style. Aware that he himself would vanish forever, Senju took solace knowing his art lived on in a worthy hearted man.
At around some time before then, Momohime was attacked by Jinkuro and died in Jinkuro's failed attempt to claim the body of Yagyu Yukinojo, after being afflicted with a curse that ate away his physical strength and health. As a result, Jinkuro, bound to Momohime's body, was able to avoid death and continue to rampage.