This is a tourism ad. That needs to stop being the reason to dismiss it. A single episode holding the weight of a real woman's life across the Sengoku Era, jumping between her present and the castle that defined her, is a kind of storytelling most prestige anime never attempt. The show treats Oam's coming-of-age not as backdrop for battles or politics, but as the actual history that survived. It builds something quiet and specific: what it cost a noble woman to watch the world burn around Ogaki Castle, and what she remembered when it was over. Most people never hear about this one. Most people should.
Made to promote tourism in Ogaki City, Gifu Prefecture, this single-episode ONA adapts Oam Monogatari, a book about a woman who came of age during Japan's Sengoku period. Oam is the daughter of Yamada Kyoreki, a retainer of the warlord Ishida Mitsunari, and her account is one of the rare records of a noble young woman's life in wartime. The story moves back and forth between past and present, showing Oam's hardships at Ogaki Castle, which later became central to the Battle of Sekigahara, and her escape with her mother late one night.