Endō Motonobu served as a bushō during the Sengoku and Azuchi-Momoyama periods. Motonobu was a retainer of the Date clan of Mutsu Province. Motonobu was born as the son of the abbot of the Saikō Temple located below Hatchōme Castle in the Shinobu District of Mutsu Province.
During his early years, Motonobu traveled several provinces and then visited Yonezawa in the Okitama District of Dewa Province where he served the Date family. Initially, he served Nakano Munetoki, an influential retainer of Date Harumune. Later, just before Munetoki launched a rebellion against Date Terumune, he secretly informed Terumune of the plot for which he was praised and elevated to serve as a clan elder under the command of Terumune. At this time, he was awarded a fief of 1,500 koku.
Motonobu excelled in diplomacy, frequently exchanging letters and engaging in negotiations on behalf of the Date with Oda Nobunaga, Tokugawa Ieyasu, Hōjō Ujiteru, and Shibata Katsuie. Motonobu encouraged Terumune to actively promote friendly relations with Nobunaga. On numerous occasions, Terumune sent gifts to Nobunaga such as falcons, horses and specialties from the Ouu Region. In this manner, Motonobu served as the representative of the retainers of the Date clan during Terumune’s administration.
Further, Motonobu engaged in renga, or linked-verse poetry, with Asukai Masanori, a noble who served as the chief messenger of the military families to the emperor. It is surmised that these experiences contributed to his succession to the influential role of Nakano Munetoki (as Munetoki was formally managing relations with the Asukai family) and that his cultural pursuits enabled him to develop a network for purposes of engaging in diplomacy for the Date in Kyōto and with assorted daimyō.
While still young, Motonobu was recognized by an influential military strategist of Date Masamune named Katakura Kagetsuna who had Motonobu served as an assistant. According to Masamune’s memoirs, Motonobu was a very bright individual possessing the foresight to predict (eight out of ten times) events to occur in the following year.
In the tenth month of 1584, after Terumune transferred headship of the clan to Masamune and retired, Motonobu then followed suit and retired in the eighth month of 1585. However, on 10/8 of Tenshō 13 (1585), Terumune was abducted by Nihonmatsu Yoshitsugu who held grievances toward Masamune. Yoshitsugu and all those with him, including Terumune, were shot with arquebuses by Masamune’s soldiers, resulting in a violent demise. On 10/21, Motonobu marked a day of grieving for Terumune by martyring himself in front of Terumune’s grave. Motonobu’s grave lies alongside those of his lord at the Shifuku Temple.
Motonobu was succeeded by his eldest son, Endō Munenobu, who died of illness at the age of twenty-two in 1593. Munenobu was succeeded by his younger brother, Tsunenobu. Later, Tsunenobu was granted landholdings in Takino in the village of Kawaguchi in the Kurihara District. His descendants continued until the Meiji period.