Katana signed Hizen-ju Harima-daijo Fujiwara TADAKUNI

Shinto early Edo period (Latter half of Kanei era/about 370 years ago) Hizen
Length of cutting edge71.1cm Curvature1.7cm Width of base28.6mm Thickness of base7.2mm Width of Yokote18.1mm

Reference only 

Blade construction: Shinogi-zukuri, Iori-mune in low, Mihaba is moderate standing firmly with lower pointed deep curvature and upper area curved as well leading to a middle point. The entire shape is well proportioned and gracefully beautiful.(click HERE for higher resolution image of the entire blade)
Forging(Hada): Forging is conspicuous Itame mixing with large Mokume-hada indication. Taste of fine steel gives off moistened impression by sparkling ji-nie glitter that generates rich and thick Nie lines of grain pattern so called CHIKEI activity.
Temper(Hamon): Hamon is fine Nie hard metal granules base, starting with straight Yakidashi shortly underneath habaki then flamboyant frequent Choji-outline "clove outline" which varies in height and shape such as long footed, large clustered or cross over. The interior of temper is filled with mist-like crystallize area deeply with ASHI and floating YOU activities, thick lines of nie SUNAGASHI and bright curved threadlike KINSEN areas. Deep sparkling Nie accumulates on the gorges of Clove-outline and a pair of round head forms likely "eyes of horsefly" so called "Abunome". The entire temper is full of flamboyant impression.
Temper of tip(Boshi): Temper of boshi forms straight with frequent thick lines of Nie then medium circle turns back gently.
Tang(Nakago): Nakago is in UBU original. One peg hole. Greatly slanting left (O-sujikai) filemarks. Back ridge of Nakago is flat and V-shape (kengyo) heel of which summit is filed away in flat. The signature in the reversed side is eleven character that starts from the place of work Hizen-ju 肥前住 and an official district Harima-daijo 播摩大掾 title, name of clan Fujiwara 藤原 and the smith name TADAKUNI 忠国.
The first generation TADAKUNI 忠国, real name Hashimoto Rokurozaemon 橋本六郎左衛門, was the second son of HIROSADA 広貞、real name Hashimoto Souemon-no-jo 橋本相右衛門尉 who was younger brother by different mothers of 1st generation Hizen-koku TADAYOSHI 肥前国忠吉.TADAKUNI 忠国 was born in keicho 9 (1604) and learned from his master, father HIROSADA 広貞 to name himself HIRONORI 広則. Among Hizen sword makers of head legitimate and 2 major branches, TADAKUNI 忠国 is older than cousin MASAHIRO 正広 by 3 years and 10 years older than 2nd gen. legitimate TADAHIRO 忠広. Those top skilled sword makers in Hashimoto family sometimes had ghostmade/signed for their great master 1st gen. TADAYOSHI in his later ages.
The first generation TADAKUNI 忠国 enjoyed an official district Harima-daijo 播摩大掾 title and changed smith name from HIRONORI 広則 to TADAKUNI 忠国 in Kanei 11 (1634) when he was 34 years old. He served exclusively to a feudal lord
Nabeshima MOTOSHIGE 鍋島元茂 in Ogi district Saga 小城. on after Shouho 1 (1644-) and had changed his style of sign that would come from a change in his state of mind. In his later ages Kanbun era (1661-), he gave the Harima-daijo 播磨大掾 title back and obtained the upgraded title of Harima-no-kami 播磨守. Passed away in the 22nd day, 4th month, Genroku 4 (1691) was 88 years old.
The subject katana, distinguished from the style of signature, was made on about 1640 in decade, his earlier stage sooner ages after he enjoyed Harima-daijo title in 1634 but before he changed his signature style on about 1644. The style of filemark in these ages is remarkable greatly slanting left and angle of V-shape heel is steep slope with it's summit is filed off in flat. For those characters of tang would be intentionally made to discriminate the difference from the other Hizen swords or works of his son.
In compare with the other Hizen swords, the hamon is the most gaily decorated with vividly bright hard metal granules with rich activities of mist-like crystalline area, thick lines of nie, short lines of nie and bright curved threadlike areas. This is an example that among Hizen swords in Edo period, 1st gen. TDADKUNI's work is the most fascinatingly splendor in Clove hamon and well-balanced proportioned shape as well.
Gold foiled single layer Tachi-style Habaki collar, preserved in Shira-saya plain wood mounting
Skilled polish/Condition scale: excellent - mint-excellent (using a scale of mint-excellent-very good-good-fair-poor).
reference :
Yokoyama Manabu Hizento Bibouroku 2006
Token Bijutsu #665 2012
Kataoka Ginsaku Hizento Shiko 1974