Akai Hayate tells the tale of a secret ninja organization called Shinagara which has controlled Japan for "thousands of years." Its strongest warriors use "Shadow Armor"(mecha-like suits constructed from magic and shadows) and named attacks to fight:
As the story begins, Kanuma Hayate, the son of Shinogara's leader, Kanuma Tanzou, suddenly and inexplicably assassinates his father. As a result, Shinogara splits into warring factions, with three of its six Shadow Warriors (Sanezuna, Miyabi, and Genbu) supporting the new leader, Ranotei, and the other three (Hayate, Date Ikkaku, and Satomi Shuri) in rebellion. The Shinogara loyalists hunt down and mortally wound Hayate. To survive, he transfers his spirit into the body of his sister, Shiori. She must now evade Shinogara's myriad assassins and unravel the mystery behind her father's death, with the intermittent help of the other rebel warriors. The show has a very somber tone, with lots of violence and violent deaths. (There's a bit of nudity and sex too, typical of an OVA from that era.) As might be expected in a civil war, there are no winners and no happy ending.
N.B. It was released an OVA in 1991 (4 episode)