Lifespan: Unknown to 8/2 of Tenbun 20 (1551)
Other Names: Hachirō-tarō, 祥山全吉
Rank: sengoku daimyō
Clan: Kazusa-Takeda (Mariyatsu family)
Father: Mariyatsu Jokan (Nobukiyo)
Siblings: Zenkan (Takeda Taifu), Nobutaka, Nobumasa
Mariyatsu Nobutaka served as a sengoku daimyō of Kazusa Province. He was a member of the Kazusa-Takeda clan (the Mariyatsu family). Nobutaka served as the lord of Minegami, Tsukuroumi, and Shiizu castles in Kazusa.
Nobutaka was born as the eldest (illegitimate) son of Mariyatsu Jokan (Nobukiyo), a sengoku daimyō in Kazusa. In 1533, an internal conflict in the Satomi clan of Awa Province occurred which is known as the Inamura Incident. In this event, Nobutaka’s father, Jokan, supported Satomi Yoshitoyo, but other members of the Mariyatsu family backed his rival, Satomi Yoshitaka, in a contest for control of the Satomi clan. According to one theory, Nobutaka sheltered Yoshitaka at his residence either at Minegami Castle or at Tsukuroumi Castle. In 1534, the conflict in the Satomi clan culminated in the Battle of Inukake in which Yoshitaka prevailed. Meanwhile, Jokan died that same year. His lineal heir, Taifu (Zenkan), also died around this time. After the death of Jokan, the Mariyatsu-Takeda became further subordinate to Hōjō Ujitsuna of Sagami Province. Under the current theory, Nobutaka was serving as the head of the clan at this time.
Before long, Nobutaka competed with his younger brother, Mariyatsu Nobumasa, for the seat of the successor. From around 1537, disputes between the factions began to escalate. This is known as the Kazusa Disturbance (Kazusa sakuran). Based at Minegami Castle, he added Tsukuroumi and Tenjindai castles to his territory. To oppose Nobumasa (who was backed by Ashikaga Yoshiaki – the Oyumi kubō), he requested reinforcements from the Satomi and Gohōjō clans to enable stiff resistance. Nevertheless, he was defeated, vacated Minegami Castle, and surrendered to Yoshiaki. After departing Minegami Castle, he holed-up in Tsukuroumi Castle. He was then attacked by Satomi Yoshitaka who had switched sides to Yoshiaki. There is a legend that, in the course of negotiations, Nobutaka requested the Satomi forces compose one hundred waka of the picturesque surroundings and, on the condition the lives of those defending the castle be spared, he would vacate the castle. After the Satomi composed and delivered the poems, Nobutaka relinquished the site which was thereafter referred to as Hyakushu Castle meaning the castle of one hundred poems.
During the Kazusa Disturbance, reinforcements of the Satomi army were stationed in Hyakushu Castle. Nobutaka relied upon the Gohōjō to flee to Kanazawa in Musashi Province and retired.
In the Mariyatsu-Takeda family, Nobumasa became the lord while Mariyatsu Zenhō (Nobuaki) and Mariyatsu Yoshinobu (father and son) of Sanuki Castle held the real authority. In 1538, at the First Battle of Kōnodai, the death of Ashikaga Yoshiaki (the Oyumi kubō) undermined the power of Nobumasa who had relied upon him. Meanwhile, with the backing of Hōjō Ujitsuna, Nobutaka returned to Kazusa, established a base a Shiizu Castle and restored his authority. To maintain his power, Nobumasa joined forces with the Satomi clan and, from around 1541, once again, the Mariyatsu family confronted internal conflict, occurring at Sasako and Nakao castles. Nobutaka killed Takeda Nobushige of Sasako Castle who he came into conflict with based on slander from retainers in the Gotō and Tsurumi clans but, before long, he was cursed with illness and died.
Taking advantage of the internal conflict besetting the Kazusa-Takeda (Mariyatsu), the Gohōjō and Satomi clans both sent forces to further intervene in their sphere of influence. In particular, Masaki Tokishige, a retainer of the Satomi clan, made advances at a rapid pace. In 1544, Mariyatsu Tomonobu, the lord of Ōtaki Castle in the Isumi District and a mainstay of Nobutaka’s faction, was killed as a result of Tokishige. The conflict weakened the Mariyatsu family. Following the deaths in succession of Nobutaka and Nobumasa in the period around 1551 to 1552, they disappeared from the stage of history.