Oyumi-kubo was one of Kubo (shogunate) families of the Ashikaga clan (of Motouji-ryu or the Motouji lineage) in Kanto region. The name has its origin in Oyumi-jo Castle in Chiba County of Shimousa Province (the present whole area of both Oyumino, Midori Ward, Chiba City & Omi, Chuo Ward, Chiba City), where they established their base. Although it was a branch family of Koga-kubo (descendants of one of the Ashikaga families that held the office of the Kanto region administrator), the both families battled each other for supremacy, but it was inherited through two generations from Yoshiaki ASHIKAGA to Yorizumi ASHIKAGA and became the foundation for the Kitsuregawa clan in later years.
Appearance of Yoshiaki ASHIKAGA
The Kamakura-kubo family, who were the forefathers of Koga-kubo, ruled the Kanto region for generations from the era of Motouji ASHIKAGA, who was the son of Takauji ASHIKAGA. The family, however, began to show its opposition to the Ashikaga head family (the Kyoto shogunate family whose forefather was Yoshiakira ASHIKAGA) over the shogunate's succession and so on. In the end, during the era of the fourth Kamakura-kubo Mochiuji ASHIKAGA, the conflict resulted in an armed clash (the Eikyo War) with the sixth shogunate Yoshinori ASHIKAGA. Mochiuji was defeated in the war and forced to commit suicide, which temporarily overthrew the Kamakura-kubo family. Most of Mochiuji's orphans were also killed by Yoshinori in the Yuki War or in other wars. After Yoshinori died in the Kakitsu War, however, calls for the restoration of the Kamakura-kubo grew, and Shigeuji ASHIKAGA (an orphan of Mochiuji) returned as Kamkura-kubo.
After grown up, Mochiuji confronted the bakufu and the Kanto Kanrei (a shogunal deputy of the Kanto region) Uesugi clan (in the Kyotoku War), and Mochiuji was expelled from Kamakura during the war. In 1455, however, Mochiuji based himself at Koga-jo Castle in Shimousa Province and retained his power independently there ever since he was called Koga-kubo. After the death of Shigeuji, internal conflicts frequently occurred in the Koga-kubo family, one of which was that between the second Koga-kubo, Masauji ASHIKAGA, and his son and the third Koga-kubo, Takamoto ASHIKAGA (the Eisho War).
Takamoto had a younger brother "Konen," who was a Buddhist priest. And in Kazusa Province there was the Mariya-Takeda clan, which was a branch family of the Kai-Takeda clan. Nobunaga TAKEDA (the second son of Nobumitsu TAKEDA), who had became a vassal of the Koga-kubo, Shigeuji ASHIKAGA, invaded Kazusa Province as ordered by Shigeuji, and embezzled the territory of the Kanto Kanrei Uesugi clan in the province, based on which event the Mariya clan emerged and became a warlord. Nobuyasu Mariya (Jokan), the fifth head of the Mariya clan, had the ambition of bringing Kanto region under his control. However, as there were influential families nearby, such as the Yuki clan, the Chiba clan, both of which had close relationship with Koga-kubo, the Mariya clan had no choice but to fall under the sway of their influence. And so, Nobuyasu had his eye on Konen. Around the early Eisho era, Nobuyasu had Konen return to secular life by changing his name to Yoshiaki ASHIKAGA, and brought him into Oyumi-jo Castle in Shimousa Province to make him Oyumi-kubo. Installing Yoshiaki as just a figurehead, Nobuyasu himself held the real power and extended his own influence over the whole of the Kanto region under the pretext that Yoshiaki belonged to the Ashikaga family. There are two different views on the year of Yoshiaki's entering into Oyumi-jo Castle: 1517 and 1522. The Mariya clan subsequently reached its prime in the era of Nobuyasu, but Oyumi-kubo was just a puppet regime of the Mariya clan at the time.
The rise and fall of Oyumi-kubo
However, Yoshiaki was not the sort of person who could be satisfied with being just a puppet. During the Inamura incident that occurred within the Satomi clan, Yoshiaki ordered Nobuyasu MARIYA to support Yoshitoyo SATOMI, who was cooperating with Oyumi-kubo. However, Yoshitoyo was killed by Yoshitaka SATOMI. This triggered the conflict between Yoshiaki & Nobuyasu. Once Yoshiaki won the conflict, he forced Nobuyasu to retire and become a priest. Nobuyasu died in 1534. The cause of his death is said to have been some disease, but there is also a theory that says he was poisoned by Yoshiaki. After a while, a successive dispute occurred within the Mariya clan between Nobutaka MARIYA & his younger half brother Nobumasa MARIYA. When Yoshiaki intervened in the dispute, he brought Yoshitaka SATOMI to his side, backed up Nobumasa, and expelled Nobutaka. In this way, Yoshiaki freed himself being a figurehead and gained power as the official Oyumi-kubo. He conflicted with the Koga-kubo family of his same blood and the Gohojo clan, and rapidly extended his power on the pretext of integrating the feudal lords in the southern Kanto region by the Oyumi-kubo family.
This rapid expansion of the influence of the Oyumi-kubo family had set the Gohojo clan and the Koga-kubo family on their guard, which resulted in the alliance between these two families. To prevent Koga-kubo and the Gohojo clan from joining forces, Yoshiaki decided in 1538 to lead the armies of Nobumasa MARIYA, Yoshitaka SATOMI, and other feudal lords from the Boso Peninsula into a decisive battle against the allied forces of Ujitsuna HOJO and Haruuji ASHIKAGA. This was what we call the First Konodai Battle. With his great military prowess, Yoshiaki took command and fought so bravely at the front of the battle that his army overwhelmed the allied forces of the Hojo and the Ashikaga for a while. However, the army of the Satomi clan was not so cooperative in the battle because Yoshitaka had been reluctant to support the battle from the beginning. Some people within the Mariya clan were offended by Yoshiaki's intervention in the dispute over the succession. Therefore, on the whole, the morale of Yoshiaki's forces composed of feudal lords in the Boso Peninsula was relatively low. Before long, Yoshiaki's forces were completely destroyed by the counterattack from the Hojo clan's forces, and Yoshiaki himself was killed in the battle. As Oyumi-jo Castle was retaken by the Chiba clan under the support of the Hojo clan after Yoshiaki's death, the surviving members of his family fled to Awa Province asking for the help of the Satomi clan. This practically put an end to Oyumi-kubo.
After the battle
The end of Oyumi-kubo enabled the Hojo clan to strengthen its base and establish its supremacy in southern Kanto region. Due to the death of Yoshiaki, the dispute over succession occurred again between Nobumasa and Nobutaka in the Mariya clan, which resulted in the rapid decline of the family fortunes. Before long the Mariya clan was attacked by the Satomi clan, and in the end they became retainers of Ujiyasu HOJO.
Among the surviving family members of deceased Yoshiaki, his first daughter, Shogakuni, was initially sheltered as a nun in the Taihei-ji Temple in Kamakura. Later, she became the lawful wife of Yoshihiro SATOMI, who was the legitimate son of Yoshitaka SATOMI, by accepting his marriage proposal. With this marriage, most former vassals of Yoshiaki became retainers of the Satomi clan.
Meanwhile, Yoshizumi ASHIKAGA, the heir of Yoshiaki, was killed along with his father in the battle at Konodai. Yorizumi ASHIKAGA, the second son of Yoshiaki, grew up under the patronage of the Satomi clan after his father's death. Afterward, Yorizumi drifted from one province to another for some time, and after a while, his daughter became a concubine of Hideyoshi TOYOTOMI, the then Tenkabito (ruler of the country). After the Siege of Odawara (the war waged by Hideyoshi against the Hojo clan) broke out, Yorizumi defeated the Chiba clan and recovered the Oyumi-jo Castle under the support of the Satomi clan, which led to the resurgence of Oyumi-kubo even only for a few months. In the report of Nagatoshi YAMANAKA, a vassal of the Toyotomi clan, regarding the postwar settlement of Kanto region, which was addressed to his counterpart, Nagamori MASHITA, it was also indicated that Yorizumi had been in Oyumi. After the Hojo clan fell, Kunitomo ASHIKAGA, the first son of Yorizumi, was allowed at Hideyoshi's discretion to marry Ujihime ASHIKAGA, the daughter of Yoshiuji ASHIKAGA (the last Koga-kubo). Together they started a new branch of the Ashikaga family called the Kitsuregawa clan, enabling the continuation of Yoshiaki's family line.
Even in the Edo period, considering the background of the Ashikaga Family as the former shogunate, Ieyasu TOKUGAWA granted Kakaku (the family status) equivalent to the yield of 100,000 koku to Yoriuji ASHIKAGA, who had originally been entitled to only 4,500 koku, and allowed the family to continue as the Kitsuregawa clan. It was an exceptional case in which the feudal domain yielding less than 10,000 koku in fact was approved to exist as clan.
Reign of Oyumi-kubos
Yoshiaki ASHIKAGA - from (supposedly) 1517 to 1538
Yorizumi ASHIKAGA -(supposedly) 1590