At the foot of Mount Tegara in Himeji, Harima province, a family of smiths took the mountain's name as their own across successive generations, descending from the first-generation Yamato no Daijō Fujiwara Ujishige. The trace this Banshū line through its best-documented figure, Tegarayama Masashige, commonly called Asashichi or Chōshichi and using the art name Tankasai. He was the younger brother of the third-generation Tegarayama Ujishige, first succeeded to the name of the fourth-generation Ujishige, and only later changed his signature to Masashige. In Tenmei 8 (1788) he entered the service of Matsudaira Sadanobu, lord of Shirakawa in Ōshū, as a retained smith (kakae-kaji) and moved to , where he resided at Surugadai in Kanda; in the fourth month of Kyōwa 3 (1803) he received the honorary title no Kami. One records that in he studied under Suishinshi Masahide. Around the start of the Bunsei era he forged for a time in Osaka before returning to , and from his lord Rakuō he was granted the two characters "Shinmyō," which he cut on the works he held most successful.
The hand the describe is a -toned revival built on the tōran-midare of Tsuda no Kami Sukehiro, whose style Masashige privately admired (). The forging runs to tightly compacted with adhering thickly, fine entering, and at times a quiet near- ground; the steel reads clear. Most blades open with a or at the base and then rise into a billowing tōran-style large , mixed with , slightly pointed () elements, and arrow-nock () shapes likened to surging waves. The temper carries deep , evenly adhering , and , with and threading the edge and , , and breaking out above it; the tends bright. The is generally ending in , sometimes with and a long . Beyond this signature manner he also worked shallow of wide and plain , so the orderly large that refuses to collapse, the pointed accents within the , and the wide of his forms serve as the readiest marks of his work.
Across the register the points cluster around that controlled tōran and its lively and , while one , mingling into the edge, prompts the observation that Gonnoshin Terukane may also have been in mind. Self-carved recur and aid attribution: jewel-chasing and ascending or descending dragons, , the sankō-tsuka-ken, and , with tangs reading "hori dōsaku" to record the smith's own chisel. Several inscriptions carry documentary weight, naming Surugadai and Shundai in Buyō as places of forging, Ishū Dewa iron also used by Katayama Munetsugu, and a commission for Kosugi Tamenaga, a retainer of the domain; a signed "Ōshū Shirakawa kashin Masashige" bears self-cut dragon, , and sankō-tsuka-ken recorded on its tang. The blades signed with bold, thick-chisel over tangs finished in , dated through the Kansei and Kyōwa years, mark Tegarayama as a Himeji-rooted line whose strength lay in the recreation of Sukehiro's waves.