- Born: 1571
- Died: 1637
- Sons: Niwa Mitsushige
- Titles: Kaga no kami
- Other names: Gorôzaemon, Hashiba Nagashige
- Distinction: Toyotomi retainer
Nagashige was a son of Niwa Nagahide and was born on 11 May 1571. He participated in the Komaki Campaign in place of his ill father and engaged the forces of Sasa Narimasa. Following Nagahide's death, Nagashige was transferred to a 40,000 koku fief in Kaga province, thus considerably reducing the power of the Niwa clan, though Toyotomi Hideyoshi's ulterior motives for doing so are unclear. His domain, based at Komatsu, was increased to 100,000 koku in 1598. He elected to side with Ishida Mitsunari and fought against Maeda Toshinaga. After the Tokugawa victory he was deprived of his holdings but nonetheless went on to distinguish himself on the Tokugawa side at the Osaka Castle Campaigns. For this service he was given a 10,000 koku fief at Futto in Hitachi province. He was then moved to Shirakawa han in 1627. Niwa was named to the post of sangi (councilor) in 1632, and as a result was sometimes referred to as Niwa Saishô. He died on 1 April 1637.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005
- Yamamoto Hirofumi, Sankin kôtai, Kodansha gendai shinsho (1998), 192.
- Arai Hakuseki, Joyce Ackroyd (trans.), Told Round a Brushwood Fire, University of Tokyo Press (1979), 281n41.