Oblong round shape (nagamaru-gata) tsuba with design of dragonfly (tombo or katsumushi) and wheel (kuruma) in negative openwork (kage-sukashi), round rim (maru-mimi ). Copper sekigane.

Okamoto Yasukazu's Owari to Mikawa no tankō, №181 characterizes the tsuba as follows: "Katsumushi, kuruma-sukashi no zu (dragonfly and wheel sukashi). Mei: Yamakichibei (Shodai). Such small tsuba are rare for the Shodai. The nakago-ana is also small so it was probably intended to be mounted on a tantō. Regardless of its size, the iron is outstanding and the workmanship shows the characteristic features of the Shodai (first generation). The kuruma-sukashi design is interpreted here in a half-moon shape and only on one side of the tsuba. Such a design is also seen on works of the Nidai (second generation)...". Signed to the left of nakaga-ana: Yamakichibei (山吉兵へ). Attributed to the First Generation (Shodai) master.

NBTHK paper (translated by Markus Sesko): The Tokubetsu-Kichō Kodōgu. Kachimushi-kuruma sukashi-tsuba (勝虫車透鐔) - Tsuba with sukashi motif of dragonfly and cartwheel. Signed: Yamakichibei (山吉兵). Iron, marugata, ko-sukashi. Issued on April 1, 1977. [Copy only] Dimensions: H: 66 mm; W: 63.2 mm; Th(center): 3.8 mm; Th(rim): 3.5 mm. Weight: 68 g.

A very large and very thin iron tsuba of round form decorated with design of formalized butterfly and dragonfly in openwork (sukashi). The characteristics of the plate resemble those of Kamakura period ko-tōshō tsuba. However, the design seems too 'modern' to me, but it's hard to tell; it may be a late Muromachi or Momoyama period work. Tōshō or Ko-Tōshō school (or a Katchushi). Muromachi period. However, Boris Markhasin and Skip Holbrook insist this is a 20th-century machine-made tsuba. Dimensions: 99.6 x 100.5 x 2.1 mm. This is what Jim Gilbert says about old tsuba:

"Traditionally the old iron plate tsuba are classified into Ko Tosho (old sword smith), and Ko Katchushi (old armor maker) styles. It is sometimes difficult to justify attribution of a given tsuba to the Tosho or Katchushi category. Generally guards with raised rims or relatively complex designs tend to be assigned to Katchushi. This is basically a convention we follow out of habit and convenience." [...] "In Token Kai-Shi part six, Articles by Akiyama Kyusaku, Robert Haynes comments: "…from 1300 to 1400 over 150,000 MOUNTED swords were made in Japan for export alone. This means that over four tsuba a day were made for 100 years. This would mean that at least 3000 persons were making nothing but tsuba, let alone all the other fittings needed to complete these swords. With sword smiths, fittings makers and all the other artists need to complete a sword for export, at least 10,000 sword artists were working together, in any one of these hundred years."

Another tsuba of similar design, Tōshō school, is illustrated in this collection; see TSU-0319.2015. Reference to this design can be found in LIB-1359.2017 Japanese Swords and Tsuba from the Professor A. Z. Freeman and the Phyllis Sharpe Memorial collections, Sotheby's, London, Thursday 10 April 1997; p. 18-19, lot № 37: "A Kamakura-bori Tsuba, Momoyama Period. ...pierced with two large formalised butterflies..."  

Iron tsuba of round form decorated with two boar's eyes (inome) and two dragonflies (tombo) in small openwork (ko-sukashi) outlined with brass wire. The plate also decorated with 2 to 5 concentric circular rows of brass dots (nail heads) in ten-zōgan. Center of the plate outlined with the inlaid circular brass wire. The inlaid metal is of red-ish hue, so it may be copper, and not brass. The surface has remnants of lacquer. Ōnin school. Mid Muromachi period, middle of 15th century. Dimensions: Diameter: 90 mm, thickness: 3.2 mm. Notes regarding design: "According to various sources, the dragonfly (tombo) is emblematic of martial success, as various names for the insect are homophones for words meaning "victory". The dragonfly is also auspicious because references in the Kojiki and Nihongi link it in both name and shape to the old kingdom of Yamato."  [Merrily Baird. Symbols of Japan. Thematic motifs in art and design. Rizzoli international publications, Inc., 2001, p. 108]. "The dragonfly (tonbo), was also called kachimushi in earlier times, and due to the auspicious literal meaning "victory bug" of the characters of this word it became a popular theme on sword fittings." [Iron tsuba. The works of the exhibition "Kurogane no hana", The Japanese Sword Museum, 2014, p. 13]. Two other cutouts - in the form of what in European tradition symbolizes the heart, on the top and in the bottom of tsuba disc - may have two different explanations. The most usual one, inome - "Heart-shaped pattern, which is said to go back to the shape of a wild boar's eye" [Markus Sesko. Encyclopedia of Japanese Swords. Print and publishing: Lulu Enterprises, Inc., 2014.]. This understanding is shared by Robert Haynes [Robert E. Haynes. Study Collection of Japanese  Sword Fittings. Nihon Art Publishers, 2010.] and elsewhere, with an exception of Okabe-Kakuya [Okabe-Kakuya. JAPANESE SWORD GUARDS. Museum of Fine Arts, Boston. In cooperation with the department of Chinese and Japanese art; - 1908, p. 14], who provides the illustration of inome-shaped cut-outs with the following explanation: " The tsuba shown in Fig. 13 approaches a square form with rounded corners and is perforated with Aoi decoration. But this book was written long time ago, when people even at MFA might not know enough... The same interpretation of the said heart-like symbol (aoi leaf) is given at Helen C. Gunsaulus. Japanese sword-mounts in the collection of Field Museum. // Publication 216, Anthropological Series, Volume XVI; Chicago, 1923; p. 54: "This mokkō-formed tsuba recalls the aoi form, perforated as it is with the four aoi leaves." It is possible that the "wild boar's eye" theory was developed by later scholars.   There is also a theory, supported by Graham Gemmell, saying that: “In simple terms Onin works are decorated Ko-Katchushi tsuba. … But, not content with iron alone, they began to decorate it with what was, in the early Muromachi period, a rare and valuable metal, brass. The Onin workers cut the design into the iron, using narrow channels, cast the brass, piece by piece, and then hammered it into the iron plate as though they were putting together a jigsaw. When complete the tsuba would be black lacquered exactly as the plain iron ones had been, the brass shining dully through it in a way that fulfilled the goal of shibui or restrained elegance.” [Tosogu. Treasure of the samurai. Fine Japanese Sword Fittings from The Muromachi to The Meiji Period, by Graham Gemmell. // Sarzi-Amadè Limited, London, 1991. An exhibition held in London from 21st March to 4th April, 1991]. The following illustration from Helen C. Gunsaulus. Japanese sword-mounts in the collection of Field Museum. // Publication 216, Anthropological Series, Volume XVI; Chicago, 1923; pp. 43 supports the idea. Helen C. Gunsaulus' description of the dragonfly emblem is as follows: "This motive, the dragon-fly  (akitsu), is generally accepted as a symbol of the kingdom of Japan, and the origin of the idea is traced to the legend recounted in the Kojiki and Nihongo of the Emperor Jimmu's view of the island from mountain top. He is said to have thought the kingdom looked like a dragon-fly touching its tail with its mouth. From this it received its name Akitsu-shima... etc."