Sengoku Collection - Season 1 Episode 19 Vengeful Fang-IS

Upon arriving in the modern world, Akechi Mitsuhide had lost her memory and has since become a police detective alongside her assistant, Kibayashi. She is brought on to investigate the murder of a girl named Ayako Hototogisu who was found naked and beheaded with a knife in her chest. As they wittle down their suspects, Mitsuhide becomes bothered by a masked person named Morilanty who shows up to observe the crime scenes. Coming to a realisation, Mitsuhide chases after Morilanty, discovering her to be Kibayashi, with the real Morilanty posing as her assistant. They soon accuse Mitsuhide of being the true murderer, believing the corpse was only headless as it belonged to Nobunaga. The whole thing is soon revealed to be a dream, as Mitsuhide awakes with her memory restored, believing she had really killed Nobunaga.