Nyūta Chikazane served as a bushō during the Sengoku period.  He was a retainer of the Ōtomo clan, the sengoku daimyō of Bungo Province.  Chikazane was the tenth head of the Nyūta clan and served as the lord of Tsugamure Castle.

Chikazane was born as the eldest son of Nyūta Chikakado.  The Nyūta were members of the Ōtomo clan with landholdings in Nyūta in the Naoiri township.  Although his birth year is not certain, it is surmised to have been prior to 1502, the birth year of his brother, Kutami Akiyasu, who inherited the Kutami clan.

Chikazane was well-liked by Ōtomo Yoshiaki, becoming a member of the kabanshū, or senior-ranking elders, in the clan.  Chikazane served as a mentor for Yoshiaki’s eldest son, Ōtomo Yoshishige (Sōrin).  Chikazane, however, did not get along well with Yoshishige.  Similarly, Yoshiaki (Yoshishige’s father), had conflicts with Yoshishige, preferring to have his third son, Ōtomo Shioichimaru (born to a consort), become his successor rather than Yoshishige.  Yoshiaki then plotted with Chikazane to remove Yoshishige from the line of succession by proceeding to kill retainers who favored Yoshishige, including Kozai Yamato-no-kami and Saitō Nagazane (Shigezane’s father).  The succession of killings triggered fear among the retainers in Yoshishige’s camp who then struck back.

On 2/10 of Tenbun 19 (1550), in an event known as the Collapse on the Second Floor, Taguchi Akichika, a senior member of the Ōtomo clan and leader of the faction supporting Yoshishige, together with Tsukumi Mimasaka-no-kami, attacked Yoshiaki, Shioichimaru, and his mother where they slept on the second floor of the Ōtomo residence.  Shioichimaru, his mother, and two of Yoshiaki’s daughters perished in the incident.  The attackers met a valorous end at the site of the attack.  Meanwhile, Yoshiaki died several days later from injuries sustained in the attack after recording his final wishes concerning the governance of his domain.  He was forty-nine years old.  Following his demise, retainers led by Bekki Akitsura (later known as Tachibana Dōsetsu) rallied behind Yoshishige to serve as the next head of the Ōtomo clan.

Yoshishige viewed Chikazane as a ringleader of the plot, and, upon his orders, had Akitsura pursue Chikazane.  Chikazane fled Higo Province and sought the protection of his father-in-law, Aso Koretoyo, but Koretoyo loathed him for the acts committed and Chikazane was killed.  It is surmised that Chikazane’s father, Chikakado, was killed along with him.  At the time of the Collapse on the Second Floor, Chikakado was serving as the head of the kabanshū, or senior-ranking elders, so it is possible that, even more so than Chikazane, Chikakado was targeted for elimination.

Thereafter, the Nyūta clan lost their landholdings and fell into ruin.  Chikazane’s eldest son, Nyūta Yoshizane (Munekazu), became a rōnin, or wandering samurai.  In 1578, the Ōtomo suffered a major defeat to the Shimazu at the Battle of Mimikawa, weakening the clan.  Around 1580, in view of his youth, he was permitted to return to the service of the Ōtomo clan and recovered a portion of the clan’s former territory, including 350 chō (approximately 350 hectares) in the Wakamiya manor in the Kurate District of Chikuzen Province.  He was, however, treated coldly.  In 1585, Yoshizane aligned with another retainer of the Ōtomo named Shiga Chikanori and, via Niiro Tadamoto, colluded with the Shimazu clan, playing a significant role in causing the betrayal of the Ōtomo by powerful kokujin, or provincial landowners, located in the southern portion of Bungo Province.