One-on-One Duel between Yamanaka Yukimori and Shinagawa Masakazu


Yamanaka Yukimori

Izumo Province

Shinagawa Masakazu

The One-on-One Duel between Yamanaka Yukimori and Shinagawa Masakazu occurred in the ninth month of Eiroku 8 (1565) on a sandbank in the Tonda River below Gassantoda Castle in Yasugi in Izumo Province.  Owing to the site of the duel, this event is also referred to as the Duel on the River Island.  As an outcome, Yamanaka Yukimori, a commander of the Amago army, killed Shinagawa Masakazu, a bushō under the command of Masuda Fujikane in the Mōri army.


In 1565, the Mōri clan sought to eliminate the rival Amago clan by attacking the base of the Amago at Gassantoda Castle.  This castle, however, was a stronghold, and, owing to the valiant defense by the Amago, the conflict carried on for an extended period.  Eager to gain notoriety, Masakazu committed to a one-on-one duel against Yamanaka Yukimori, a commander in the Amago army known for his superior fighting skills.

In the ninth month, seeking to down Yukimori, Masakazu changed his name to Taragi Ōkami-nosuke Katsumori and requested a one-on-one duel against Yukimori below Gassantoda Castle.  Yukimori consented to the request and committed to the duel on a sandbar in the Tonda River below Gassantoda Castle.

During this duel, soldiers from the Mōri and Amago armies faced one another across the Tonda River, and the event occurred while each side protected their respective positions.

Course of events

In this duel, Yukimori killed Masakazu and won the bout, but the details of the event differ by historical account, as described below.

Events per the Military Chronicle of Unyō dated Tenshō (1580)

Yukimori took the lead by jumping into the river and, while Yukimori was in the middle of crossing the river, Masakazu jumped in and headed toward the site of the duel.

Masakazu attempted to cross the river while affixing an arrow to a large bow, so commanders from the Amago army, including Akiage Iorinosuke (Munenobu),  Satsuki Sanaenosuke, Yabunaka Keinosuke loudly protested to Masakazu saying that readying a weapon while entering a duel was the act of a coward and that the duel was intended for the notoriety of each of them, so it should be waged with a long sword.  Masakazu, however, ignored them and crossed the river approximately 600 meters away.  Unable to bear the situation, Munenobu affixed a large two-headed arrow in his bow and launched it, breaking the string on Masakazu’s bow.

Upset that his plan of attack had been disrupted, Masakazu threw-away his bow and arrow and climbed on to the sandbar, pulled out a menacing long sword and headed toward Yukimori.  Yukimori drew his own long sword and the duel began.  After a two-hour fight, Yukimori’s skills gradually led to his advantage while Masakazu found himself cornered.  Aware that he was losing the sword fight, Masakazu proposed to Yukimori that the decide the winner through grappling, whereupon Yukimori consented and the fight evolved into a grappling match.

In this stage of the duel, Masakazu’s superior strength enabled him to pin Yukimori.  However, from below his opponent, Yukimori managed to slash Masakazu twice with a short sword in the thigh, and after a weakened Masakazu jumped back, Yukimori took his head and prevailed.  Yukimori then shouted that a deer from Izumo killed a wolf from Iwami and this was my favorite food so follow after me. (This may be a reference to Yukimori’s common name of Shikanosuke, which contains the character of a deer, and the name adopted by Masakazu before the duel, which contains the character of angelica trees that are a favorite food of deer.)  He then returned to his encampment.

This victory by Yukimori, as a member of the Amago army, stirred anger among the approximately 500 soldiers on the side of the Mōri army witnessing the event.  Concluding that they could not simply leave after one of their own was killed in front of them, they decided to launch an attack in a bid to stop Yukimori from getting away.  The Amago army responded by shooting arrows at the Mōri forces who unflinchingly made their way across the river.  Meanwhile, Tachihara Hisatsuna led two to three hundred soldiers from the castle to join the fight.  After a battalion of 100 arquebusiers began to shoot, the Mōri retreated after ten of their men were killed in action.  In this battle, was injured after being shot in his armor by three arrows from the enemy forces.

Events per the Taikōki (a biography of Toyotomi Hideyoshi) dated Kanei 3 (1626)

As Masakazu and Yukimori headed toward the site of the duel, Masakazu attempted to shoot Yukimori with an arrow, but a commander in the Amago army named Kishi Samanojō shot an arrow that broke the top portion of Masakazu’s bow so Masakazu’s failed in this attempt.

After losing his bow, Masakazu drew his long sword and a duel began against Yukimori.  Owing to his skills, Yukimori gained the upper hand in the sword fight while Masakazu sustained an injury above the elbow of his right arm.  Despite the injury, Masakazu, through his power, was winning against Yukimori so Yukimori pulled back and began to engage in a grappling match.  While the two grappled atop one another, Yukimori cut Masakazu two or three times with his short sword.  After laying face-up, Masakazu bent-up and wielded his long sword, cutting Yukimori’s shin.

Witnessing that Masakazu was losing the duel, members of the Mōri yelled not to kill Masakazu and pressed forward.  Meanwhile, the Amago forces sought to rescue Yukimori by entering the river the advancing toward the opposing forces.  Before long, however, Yukimori killed Masakazu and, after taking and showing his head, the Amago forces shouted in victory and pulled back after which the dispirited Mōri forces retreated.

Events per the Intoku-taiheiki (a historical account centered upon the Sanin and Sanyō regions during the Sengoku period) dated Genroku 8 (1695)

After Yukimori crossed the river by himself, Masakazu also jumped in and proceeded toward the site for the duel.  When the distance between the two was approximately 600 meters, Masakazu put a two-headed arrow in his large bow and attempted to shoot at Yukimori.  At this moment, Akiage Iorinosuke (Munenobu) who came after Yukimori launched an arrow that broke the string on Masakazu’s bow so Masakazu was unable to shoot Yukimori.

Upset that he could not make the attack, Masakazu discarded his bow and arrow, drew a small long sword and headed toward Yukimori.  Yukimori responded by drawing a large long sword and a sword fight began.  Owing to his skills, Masakazu gained the upper hand in the sword fight, leaving Yukimori cornered.  However, Munenobu, who was close by, went around behind Masakazu and, after slashing Masakazu diagonally from the shoulder, the situation reversed.

Having incurred a large cut on the shoulder, Masakazu fell face down and soon thereafter was held down by Yukimori and his head was taken.  Although he won the bout, Yukimori himself incurred a deep wound to a knee.  As a result, he had to be carried on the shoulders of his soldiers and returned to the main base.

After Masakazu was killed, many from the Masuda battalion of 300 soldiers in the Mōri army who witnessed the event sought to avenge their loss by banding together to launch an attack.  The Amago army, however, retreated without engaging in any clashes.  Yukimori was in danger of attack, but, through the efforts of Munenobu, Yukimori hid in a house while Munenobu carried someone else on his shoulders and fled.


Owing to his victory in this duel, Yukimori gained notoriety and raised the spirits of the Amago army.  Nevertheless, the outcome of the duel did not have an influence on the battle situation in general.  Thereafter, the Amago clan continued to deteriorate and, on 11/21 of Eiroku 9 (1567), surrendered to the Mōri and were eliminated.