Azai Nagamasa Early life and marriage . Azai Nagamasa was the son of Azai Hisamasa , from whom he inherited clan leadership in 1560 . Hisamasa had been compelled to step down by many of his retainers in favor of his son , Nagamasa . Hisamasa retired , and would later commit suicide along with his son in August 1573 . Nagamasa successfully battled both Rokkaku Yoshitaka and Saitō Tatsuoki between 1560 and 1564 . He is remembered as being a capable commander of troops on the battlefield . He married Oda Nobunaga ' s sister Oichi in 1564 . Nobunaga desired peaceful relations with the Azai clan because of their strategic position in between Oda clan land ' s and the capitol , Kyoto . Clan conflict . In 1570 , Oda Nobunaga declared war on the Asakura family of Echizen . The Asakura and Azai had been allies since the time of Nagamasa ' s grandfather . This sudden war between two Azai clan allies is reported to have divided the clan . Many retainers wished to honor the alliance with the Asakura , while Nagamasa himself is reported to have favoured staying neutral , essentially siding with Nobunaga . In the end , the Azai clan chose to honor the generations - old alliance with the Asakura and came to their aid . Initially , this decision caused Nobunaga ' s army , which was marching upon the Asakura ' s lands to retreat back to Kyoto . However , within a few months the forces of Nobunaga were again on the march , but this time they marched on Azai lands . In the summer of 1570 , Oda Nobunaga and Tokugawa Ieyasu brought an army estimated between 20 - 30 , 000 men into Northern Omi . The Azai called upon their allies , the Asakura , for assistance . The Asakura responded by sending troops . In either June or July , the two sides met at the battle of Anegawa . The combined Azai and Asakura force numbered between 15 - 20 , 000 men . The outcome is recorded elsewhere , but briefly : The battle was strongly contested by both sides . Nobunaga is recorded as having decided that his force should directly confront the numerically inferior Azai clan force , while Ieyasu would engage the Asakura . While the Oda were being held at bay , and perhaps even slowly losing ground to the Azai - who had fought against numerically superior forces in the past - Ieyasu ' s force was apparently quickly gaining the advantage against the Asakura . Ieyasu , or perhaps one of his battle commanders , decided to send part of the Tokugawa force into the Azai flank , forcing the Azai to retreat , and guaranteeing victory . However , the battle was strategically indecisive because the Oda shortly withdrew . Over the course of the next two years , with the exception of occasional interventions by the Shogun , Azai Nagamasa was under constant threat of Nobunaga aggression into Omi . Often these threats manifested into sieges of the Azai capital of Odani . During this period the Azai are seen as being loosely aligned with numerous anti - Oda forces , including the Asakura , the Miyoshi , the Rokkaku , and several religious complexes . Siege of Odani and death . In 1573 , Oda laid siege to Odani Castle . Although the Asakura sent a relief force , Nobunaga defeated this force and chased the Asakura into their lands . Shortly thereafter , the Asakura were destroyed . Nobunaga then returned south to prosecute the siege of Odani . Nagamasa had no hope of winning , and chose to commit seppuku . Before dying , he and his wife Oichi sent out their two sons to be hidden in a far place known only to them , and later sent Oichi herself and their three daughters to live with Nobunaga . Nobunaga later convinced Oichi to tell him where she had sent her infant son and Nagamasa ' s male heir , Manpukumaru , saying that he wanted the boy to live with and raise him . However , Nobunaga had Hideyoshi execute Manpukumaru , and the head was displayed on a stake . Nobunaga ensured that his sister , Oichi , was uninformed of this but she eventually came to that suspicion . There are reports that Nobunaga bore a strong grudge against Nagamasa for his perceived betrayal of their alliance even though it was he who broke the agreement first . It has also been reported that Nobunaga had the skulls of Nagamasa , Hisamasa , and the Asakura leader lacquered so that they could be used as cups , but whether this is historically accurate or merely fabricated to heighten Nobunaga ' s reputation is debatable .