Lady Otsuya (おつやの方 Otsuya no Kata) was a Japanese female samurai (onna-musha) from the Sengoku period. She was the aunt of the famous samurai Oda Nobunaga, the wife of and foster mother of Oda Katsunaga. She was the ruler of Iwamura Castle until the last days of her life. Otsuya is best known for having conspired against the Oda clan and fought against her nephew, Oda Nobunaga. Her execution under Nobunaga may have been one of the reasons for the decline in Nobunaga's reputation, who would later be murdered by Akechi Mitsuhide and others traitors in the Incident of Honnoji.