Nagateru was a son of Udono Nagamochi (d.1562?), who had held Odaka castle (scene of Tokugawa Ieyasu's famous 'Provisioning'). Nagateru's mother was a younger sister of Imagawa Yoshimoto and he enjoyed the favor of Yoshimoto's successor, Ujizane. In 1562 Nagateru was attacked at Kaminojô and killed by the Tokugawa. His two sons were taken hostage by Tokugawa Ieyasu and traded to Ujizane for Ieyasu's own family, held hostage at the Imagawa capital. Another version of this event has Nagamochi being killed at Kaminjô and Nagateru and a younger brother (Nagatada) being taken captive.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005