Azai Nagamasa was a Japanese samurai and the lord of the Azai clan during the late 16th century. He is best known for his opposition to the powerful Oda clan and his alliance with the Takeda clan. Nagamasa played a significant role in the Sengoku period, a time of intense military conflict and political intrigue in Japan. Nagamasa was married to Oichi, the sister of the famous warlord Oda Nobunaga. His resistance against Nobunaga ultimately led to his downfall, as he was defeated in the Battle of Anegawa in 1570. Despite his defeat, Nagamasa is remembered for his loyalty and bravery.