[Crossover] Both a Master and a Time-Traveling Army

Amid the raging flames of Enryakuji, Oda Nobunaga was given the name of the Sixth Demon King. Thus were born the Shadow Warrior, a man made flesh from hatred, jealousy, desire, and obsession. Amid the roaring flames of Honnoji, the Man of Flesh performed the ritual killing for Nobunaga, taking his body and claiming the Heavenly Demon Armor. He built Skull Castle and succeeded him as the Demon King. "I died in the flames, then rose again in the flames. I inherit Nobunaga's will and swear to throw this world into chaos, and to conquer you, Mori Ranmaru." Yet purity shall be the world's righteousness, and false heavens are fated to be cast down. The chaos of the Warring States will eventually subside. The real headache for the citadel is only just beginning. Swordsmen: Who would have thought the Saniwa we went to such trouble to rescue would turn out to be the leader of the Time Retrograde Army!? Time Retrograde Army: I left such an enormous Demon King right here! We were this close to changing history! ☆ Written for my own amusement. A mountain of original headcanons. Slow build. ★ Includes elements from Touken Ranbu, Nobunaga Concerto, The Seven Souls in the Skull Castle, and more. ☆ [Important] 1. Main pairing: Demon King x Mori Ranmaru; Nobunaga Concerto's two Nobunagas. 2. The protagonist belongs to the Time Retrograde Army. After their defeat, they are picked up by a regular citadel. The Warring States period is the main setting early on, the citadel takes center stage in the middle and later parts, and Nobunaga Concerto is a secondary setting. Theme: Strike down evil and uphold justice.