Naotsuna worked in Iwami, the western province the swordbooks call Sekishu, during the Nanbokucho period, signing his blades with the residence Sekishu-ju or Sekishu Dewa-ju. The old tradition counts him among the Masamune-jittetsu, the ten noted disciples of Sagami Masamune, and the published sources have transmitted that account from the Edo period onward. They do not accept it on its face. Of the first generation they write that he 'is counted among the so-called Masamune Jittetsu, yet seen in terms of chronology a direct connection seems somewhat forced, and the question must await further careful study'[[c:1]], for no extant work bears a date earlier than the Eiwa era. What can be fixed is the manner: this is the Soshu tradition carried west to Iwami, and the published sources read its current as running together with Shizu and Samonji[[c:2]].

His hand is read from workmanship rather than from signature, because signed Naotsuna are scarce. The published record notes plainly that 'signed works by Naotsuna are comparatively few'[[c:3]], and most of what survives is o-suriage and mumei, so the few signed tachi carry a weight beyond their number. The tell the judges name is a temper of squared-off, lined-up gunome, the angular teeth running in step with one another, mixed with small gunome, small notare and pointed togariba. Over a well-nie'd midare he lays vigorous sunagashi and frequent kinsuji, with ashi and yo entering often. The published commentary draws the whole picture together on one shortened blade: the jigane of flowing itame with ji-nie and chikei, worked with 'a distinctive linked gunome and togariba, with sunagashi and kinsuji, is the characteristic point of interest of Sekishu Naotsuna'[[c:4]]. That sentence is the heart of his kantei.

The jigane is the constant beneath the temper. It is an itame that flows and stands, mixed with mokume, the hada open rather than packed, with ji-nie adhering and chikei entering well, and a steel tone that runs darkish, at times with a slight whitish cast. Over that jigane the activity belongs wholly to Soshu: nie gathers thickly, yubashiri and tobiyaki drift into the upper half, and on some blades a nijuba-like line doubles the habuchi while the nioiguchi tends to sink. The boshi answers the midare below, running in irregular and swept with hakikake, pointed on one face and small-round on the other, often closing in a yakizume-like sweep. Most of the katana carry a bo-hi cut through both sides, now and then with a soe-hi beside it.

The record divides cleanly into two registers of the one hand. The first is the small body of signed tachi, several of them judged the work of the first generation and prized for being signed at all. The keystone is the Tokubetsu Juyo tachi inscribed Naotsuna in two large characters, which the published sources call 'appraised as the work of the first generation and, being signed, exceedingly valuable', and whose notare-based temper with pointed elements they liken to Shizu and Samonji. The second register, far the larger, is the o-suriage mumei katana attributed to Sekishu Naotsuna from the workmanship alone. A second Tokubetsu Juyo, a shortened katana bearing a long gaku-mei, shows the angular gunome lined up across the blade with that characteristic Soshu activity. Across these the signatures themselves differ from blade to blade, which is one reason the swordbooks have never fixed which pieces are first generation and which second, placing the generations variously at Kenmu, Eiwa and Oei.

Within the Soshu tradition his work is set beside Shizu Kaneuji and Samonji, the published sources holding that his temper 'shares an underlying current with Shizu and Samonji of the Soshu-den'[[c:5]]. What separates him is not borrowed but his own: the lined-up angular gunome and the abundant sunagashi and kinsuji over a dark, flowing itame are the features by which an unsigned blade is judged his, where a Sagami Soshu hand would show a more refined jigane and a Bizen smith a bright packed ji with utsuri. He stands as the figure who took the Soshu manner out to Iwami and gave it a recognizable provincial accent, the linked gunome his signature where the cut signature is missing.

For the collector he is a smith met almost entirely through attribution. Fujishiro grades him Jo-jo saku. He has no National Treasures and no Important Cultural Properties; his record runs instead through two pieces at the Tokubetsu Juyo rank, some sixty-nine at the Juyo, and three prewar Juyo Bijutsuhin recording signed tachi and a tanto, several from named houses. His blades are held in institutions and long-standing collections grounded in their own provenance, among them the Tokugawa Art Museum and the Tokyo Fuji Museum, with documented owners reaching back to the Tokugawa and Uesugi families, the Takatsukasa house, Ikeda Toshitaka and Tachibana Tadazane. Most designated blades, in private hands as in public, are held rather than traded, and a signed Naotsuna is rarer still than the count of designations suggests, since so little of his work is signed. An o-suriage mumei katana carrying his linked gunome comes to a private collector from time to time and with patience; an ubu, signed tachi judged the first generation is among the scarcer things one could hope to encounter, and a quiet document of how the Soshu tradition travelled to the far west.

Naotsuna worked in Iwami, the western province the swordbooks call Sekishu, during the Nanbokucho period, signing his blades with the residence Sekishu-ju or Sekishu Dewa-ju. The old tradition counts him among the Masamune-jittetsu, the ten noted disciples of Sagami Masamune, and the published sources have transmitted that account from the Edo period onward. They do not accept it on its face. Of the first generation they write that he 'is counted among the so-called Masamune Jittetsu, yet seen in terms of chronology a direct connection seems somewhat forced, and the question must await further careful study'[[c:1]], for no extant work bears a date earlier than the Eiwa era. What can be fixed is the manner: this is the Soshu tradition carried west to Iwami, and the published sources read its current as running together with Shizu and Samonji[[c:2]].

His hand is read from workmanship rather than from signature, because signed Naotsuna are scarce. The published record notes plainly that 'signed works by Naotsuna are comparatively few'[[c:3]], and most of what survives is o-suriage and mumei, so the few signed tachi carry a weight beyond their number. The tell the judges name is a temper of squared-off, lined-up gunome, the angular teeth running in step with one another, mixed with small gunome, small notare and pointed togariba. Over a well-nie'd midare he lays vigorous sunagashi and frequent kinsuji, with ashi and yo entering often. The published commentary draws the whole picture together on one shortened blade: the jigane of flowing itame with ji-nie and chikei, worked with 'a distinctive linked gunome and togariba, with sunagashi and kinsuji, is the characteristic point of interest of Sekishu Naotsuna'[[c:4]]. That sentence is the heart of his kantei.

The jigane is the constant beneath the temper. It is an itame that flows and stands, mixed with mokume, the hada open rather than packed, with ji-nie adhering and chikei entering well, and a steel tone that runs darkish, at times with a slight whitish cast. Over that jigane the activity belongs wholly to Soshu: nie gathers thickly, yubashiri and tobiyaki drift into the upper half, and on some blades a nijuba-like line doubles the habuchi while the nioiguchi tends to sink. The boshi answers the midare below, running in irregular and swept with hakikake, pointed on one face and small-round on the other, often closing in a yakizume-like sweep. Most of the katana carry a bo-hi cut through both sides, now and then with a soe-hi beside it.

The record divides cleanly into two registers of the one hand. The first is the small body of signed tachi, several of them judged the work of the first generation and prized for being signed at all. The keystone is the Tokubetsu Juyo tachi inscribed Naotsuna in two large characters, which the published sources call 'appraised as the work of the first generation and, being signed, exceedingly valuable', and whose notare-based temper with pointed elements they liken to Shizu and Samonji. The second register, far the larger, is the o-suriage mumei katana attributed to Sekishu Naotsuna from the workmanship alone. A second Tokubetsu Juyo, a shortened katana bearing a long gaku-mei, shows the angular gunome lined up across the blade with that characteristic Soshu activity. Across these the signatures themselves differ from blade to blade, which is one reason the swordbooks have never fixed which pieces are first generation and which second, placing the generations variously at Kenmu, Eiwa and Oei.

Within the Soshu tradition his work is set beside Shizu Kaneuji and Samonji, the published sources holding that his temper 'shares an underlying current with Shizu and Samonji of the Soshu-den'[[c:5]]. What separates him is not borrowed but his own: the lined-up angular gunome and the abundant sunagashi and kinsuji over a dark, flowing itame are the features by which an unsigned blade is judged his, where a Sagami Soshu hand would show a more refined jigane and a Bizen smith a bright packed ji with utsuri. He stands as the figure who took the Soshu manner out to Iwami and gave it a recognizable provincial accent, the linked gunome his signature where the cut signature is missing.

For the collector he is a smith met almost entirely through attribution. Fujishiro grades him Jo-jo saku. He has no National Treasures and no Important Cultural Properties; his record runs instead through two pieces at the Tokubetsu Juyo rank, some sixty-nine at the Juyo, and three prewar Juyo Bijutsuhin recording signed tachi and a tanto, several from named houses. His blades are held in institutions and long-standing collections grounded in their own provenance, among them the Tokugawa Art Museum and the Tokyo Fuji Museum, with documented owners reaching back to the Tokugawa and Uesugi families, the Takatsukasa house, Ikeda Toshitaka and Tachibana Tadazane. Most designated blades, in private hands as in public, are held rather than traded, and a signed Naotsuna is rarer still than the count of designations suggests, since so little of his work is signed. An o-suriage mumei katana carrying his linked gunome comes to a private collector from time to time and with patience; an ubu, signed tachi judged the first generation is among the scarcer things one could hope to encounter, and a quiet document of how the Soshu tradition travelled to the far west.