Forgeries continue to be made in every country at every age, and they will never disappear. The same is true in the world of Japanese swords. When buying or selling a Japanese sword, whether it is a genuine or a forgery is a major factor in the decision to purchase. Especially after the Shinto period, the production of tamahagane, the material used to make Japanese swords, was concentrated in the mountains of Chugoku to maintain a certain level of quality, and the development of transportation methods made it possible to obtain tamahagane of similar quality anywhere in the country. As a result, Japanese sword jigane has become very beautiful, but the regional and school-specific characteristics that existed during the Koto period have faded. In a sense, this also meant that it became easier to make forgeries, and during the Shinto and Shinshinto periods, works with false names of famous swordsmiths began to be mass- produced.

During the Shinto period, there were swordsmiths who, despite their great skills in sword making, continued to make fake swords. One of the most famous of these was a swordsmith by the name of Mishina Hirofusa, who worked in Kuwana City in present-day Mie Prefecture.

He has a venerable lineage as a swordsmith, and according to legend, his ancestor is said to have been Shizu Saburo Kaneuji, one of Masamune's disciples. Kaneuji's ninth grandson was Mutsunokami Daido, the official swordsmith of Oda Nobunaga, and Hiromichi was an orthodox swordsmith with Daido as his uncle. However, by the end of the Edo period, the demand for swords became high, and he began to make fake name pieces of works from the Sue Bizen period. Because he was active in Kuwana, these forgeries were called Kuwana Uchi. However, his workmanship was excellent, and in terms of practicality, they were superior to genuine Koto period Japanese swords. Omura Kunitaro, a Japanese sword connoisseur, described Kuwana Uchi as “Forgeries that are even better than the real". While Hirohusa made excellent forgeries, he also made excellent Japanese swords that cut well under his own name. The replica of Muramasa made under his name is said to be the best of all Muramasa replica and was said to be as good as the real Muramasa, and katanas with Hirohusa's signature were also highly acclaimed. Ironically, therefore, some of his forgeries were engraved with Hirofusa's signature on the blade of Gendaito.

Another master of making forgeries was a swordsmith named Hosoda Naomitsu, who was most adept at making Kotetsu forgeries. In particular, he reproduced not only the style of Kotetsu but also the engraving of the signatures so precisely that even today, when the study of forgery is well-developed, his works are said to be a source of annoyance to researchers. The signature of Kotetsu has not only its own peculiar style, but also shows many changes depending on the period of making the sword, and Naomitsu even precisely captured and reproduced the way Kotetsu was chiseled. Naomitsu also elaborately reproduced the false signature of Naotane, who is said to have been one of the most dexterous swordsmiths of the Shinshinto period. Perhaps the reason for this is that Naomitsu's master was Jiro Taro Naokatsu, Naotane's apprentice and Naotane's daughter-in-law, who had many opportunities to hold many famous swords in his hands.

Even though they are forgeries, they may be more than forgeries according to the person who made them.