Wazamono is a Japanese term that, in a literal sense, refers to an instrument that plays as it should; in the context of Japanese swords and sword collecting, wazamono denotes any sword with a sharp edge that has been tested to cut well, usually by professional sword appraisers via the art of tameshigiri (test cutting). The term wazamono has been popularized by two books published during the late Edo period. The first is called Kaihō Kenjaku (懐宝剣尺), a single-volume authoritative index classifying historic Japanese swordsmiths based on the quality (cutting performance) of their blades; the book's first edition was compiled and published in 1797, with re-publishings made in 1805 and 1815 due to the book's popularity. The contents, written and edited by Tsuge Heisuke Masayoshi (柘植平助方理), a samurai of the Karatsu Domain in Hizen Province, were based on the recorded cutting tests done by Yamada Asaemon V Yoshimutsu (山田浅右衛門5代吉睦), an executioner of the Tokugawa Shogunate and fifth head of the famous Yamada Asaemon (山田浅右衛門) line of sword testers; single cuts were performed on the corpses of executed criminals aged 30 to 50, cutting their torsos roughly above nipple height. The Kaihō Kenjaku identified, in total, 163 (228 if counting the "mixed" category) wazamono swordsmiths, grouped into four "grades" (位列) based on the cutting performance of their blades: The Mixed Grades (大業物・良業物・業物混合) category included 65 additional swordsmiths noted for having swords of mixed quality/sharpness level (Ōwazamono, Yoki-/Ryōwazamono, Wazamono). The 1805 and 1815 re-publishings of Kaihō Kenjaku saw adjustments be made to the rankings. In 1830, a second book, called Kokon Kaji Bikō (古今鍛冶備考), was published as a major revised list of the wazamono ratings. This new list yet again made amends to the original, and new sword makers were added, such that there were now 15 sword makers in the Saijō Ōwazamono (Supreme) category, 21 in the Ōwazamono (Excellent) category, 58 in the Yokiwazamono (Very Good) category, 93 in the Wazamono (Good) category, and 68 in the mixed category, for a total of 255 swords. This time, the cutting tests had been conducted by the 7th head of the Yamada family lineage, Yamada Asaemon Yoshitoshi (山田朝右衛門吉利). The katana forged by Nagasone Kotetsu, one of the top-rated swordsmiths, became very popular at the time when the books were published, and many counterfeits were made. Furthermore, the swordsmiths treated specially in the Kyōhō Meibutsu-chō (a catalogue of excellent swords in the collections of daimyō from the Kyōhō era) and Muramasa (famous at that time for forging swords of high cutting ability) were omitted from the listings. The reasons are thought to be that Yamada was afraid of challenging the authority of the shōgun, that he could not use precious swords possessed by the daimyō in the examination, and that he was considerate of the legend of Muramasa's curse. A misconception about the wazamono classification is that it is a sword ranking, since the term wazamono itself refers to swords; however, the grades pertain to swordsmiths, graded according to the cutting ability of their blades. See the below list of the swordsmiths listed in the Kaihō Kenjaku.

Twelve (12) Saijō Ōwazamono

The original list of 12 swordsmiths who, based on the cutting ability of their blades, hold the highest rank of Saijō Ōwazamono (Supreme Grade): In the reprinted edition released in 1805 as well as the major revised edition of 1830, the three swordsmiths Soboro Sukehiro (ソボロ助広), Osafune Kagemitsu (長船景光), and Izuminokami Kanesada (和泉守兼定 = Kanesada II) were added to the list.

Twenty-one (21) Ōwazamono

The original list of 21 swordsmiths who, based on the cutting ability of their blades, hold the second-highest rank of Ōwazamono (Excellent Grade):

Fifty (50) Yoki-/Ryōwazamono

The original list of 50 swordsmiths who, based on the cutting ability of their blades, hold the third-highest rank of Yokiwazamono (Very Good Grade), alternatively pronounced Ryōwazamono (modern reading):

Eighty (80) Wazamono

The original list of 80 swordsmiths who, based on the cutting ability of their blades, hold the third-highest rank of Wazamono (Good Grade):

Mixed

The following is the category of sword makers who, per the aforementioned listings, produced a mixture of quality: Ōwazamono, Yoki-/Ryōwazamono, or Wazamono. A total of 65 swordsmiths belong to this category:

In popular culture

In the hit manga One Piece, so-called meitō (名刀) are prominently featured: bladed weapons (usually but not strictly swords) forged by master craftsmen and wielded by powerful pirates and marines alike. The finest of these fall into a Wazamono grading system, classifying them into four grades that are directly inspired by those defined in the Japanese Kaihō Kenjaku (although notably ranking the swords themselves, rather than their smiths). Namely, there are 12 Saijō Ōwazamono blades, 21 Ōwazamono blades, 50 Ryōwazamono blades, and an unknown number of low-ranking Wazamono blades. One of the main characters, Roronoa Zoro, is notable for wielding three Wazamono swords at all times.