Period: Genroku-Gembun (1688-1736 AD)
Mei: Nio Kiyotsugu
Sugata: Shinogi-zukuri, tori-zori, iori-mune. A fairly high shinogi-ji
Overall length: 26.69 inches (678 mm)
Nagasa: 21.14 inches (537 mm) long.
Nakago: Ubu, 5.55 inches (141 mm), ha agari kiri-jiri, one mekugi-ana. The yasurime are sujikai.
Kissaki: Chu-kissaki, 1.27 inches (32.20 mm). O-maru boshi tends with some kaeri.
Moto-haba: 1.20 inches (30.40 mm). Moto-gasane: 0.27 inches (6.90 mm). Saki-haba: 0.76 inches (19.30 mm). Saki-gasane: 0.18 inches (4.6 mm).
Sori: 0.72 inches (18.20 mm)
Hamon: Gunome-midare with sunagashi, hotsure and nie-deki. A good polish would, I think, reveal a lot of activity. The hamon almost reaches the shinogi on the monouchi.
Hada: Details are a little unclear due to the polish but itame with some mokume. Further details of the hada would be drawn out with a polish.
Blade condition: In old but fine polish, minor surface scratches. No fatal flaws and no cracks. The x4 macro photographs greatly exagerate the scratches. It feels like a very strong blade.
In handachi mounts. The menuki are rather nice archery sets, probably of gold and shakudo. The tsuba is an iron 'boar's eye' design. The urushi lacquered saya is flecked with abalone. There is a very small chip of lacquer missing, but it would not be expensive to remedy that.
Kiyotsugu (Hawley KIY 566; 1688-1736) was from Nagato Province. He was the son of Kiyosane and was part of the Nio Chosu school.
The Nio school, which forms part of the Yamato Tradition, was founded by Kiyozane in the Kamakura Period and was active till the end of the Edo period. The Nio school was originally established in Suo, which was a manor of the Yamato Nara Todai-ji. This was patronized by the Tegai, and and the Nio school was therefore exposed to Yamato influences. Nio school swords thus follow the Yamato tradition in their workmanship.
In Shinto times the Nio school moved to neighbouring Chosu. They were probably sponsored in their move by the daimyo of Chosu (the Mori clan), in order to provide for the Mori clan's sword requirements.
This sword is highly unlikely to be gimei. Firstly, although the current polish partially obscures details, the work is consistent with the Nio school. Secondly, although the Nio school were good smiths who produced very workmanlike swords with good activity, they did not produce many outstanding smiths. It was the work of outstanding or famous smiths that attracted the attention of forgers, not the likes of Kiyotsugu.