Tamenari (為次) was a smith of the Ko-Aoe school in Bitchū Province, identified as the son of Ko-Aoe Moritsugu. Several smiths are recorded as having used the name "Tamenari," and the representative masterpiece among works bearing this name is the National Treasure known as "Kitsunegasaki," transmitted in the Kikkawa family of Iwakuni. That celebrated tachi is associated with Yoshika Kojirō Tomokane, an ancestor of the house, who is said to have worn it in Shōji 2 (1200) when pursuing the Kajiwara clan at Kitsunegasaki in Suruga Province. The Kitsunegasaki is regarded as exceptionally precious because, within Ko-Aoe — where dated inscriptions are entirely absent — its transmission is both early and secure. Works attributed to Tamenari, and the closely related name Tametsugu, are consistently placed in the early to late Kamakura period by the NBTHK, situating these smiths at the heart of the Ko-Aoe lineage.

Tamenari's blades characteristically display shinogi-zukuri, iori-mune construction with pronounced koshizori and a ko-kissaki or chū-kissaki. The jihada is an itame mixed with mokume, tending toward hada-dachi, with ji-nie adhering well and a clear sumihada — a lucid, refined texture — appearing as a defining hallmark of the Ko-Aoe group. An impression of utsuri is also noted. The hamon is described as an archaic (koga) composition of ko-midare and ko-chōji formed in ko-nie, frequently incorporating reverse-chōji (saka-chōji) tendencies and abundant ashi. The nioi is characteristically deep with a bright nioiguchi. The bōshi is typically straight, finishing in yakizume or ko-maru. Works attributed to the related name Tametsugu show a similar forging character but with a larger midare pattern mixing in chōji elements, lending a notably vigorous and forceful spirit. Signature characters on Tametsugu works are cut in a somewhat larger hand than those on the Kitsunegasaki, suggesting slightly later production within the lineage.

The NBTHK consistently praises Tamenari and Tametsugu works for clearly displaying "the principal points of appreciation for Ko-Aoe." Both ji and ha are described as richly flavored and evocative, with the archaic manner of workmanship affirmed as dating to no later than the early Kamakura period. Ubu, signed tachi by these smiths are valued as precious documentary material, while even shortened examples bearing orikaeshi-mei retain vigorous chisel handling and the signature style characteristic of Ko-Aoe. Within a school where secure documentary evidence is scarce, the Tamenari/Tametsugu line occupies a position of particular scholarly importance, with the Kitsunegasaki serving as the benchmark against which all other works are measured.