Here starts the Shinto time. Shinto means "new swords," and entered the common vernacular in Meiji time. It refers to swords made with new materials and new methods, both enhanced by better technologies. This is true especially for the process of extracting steel from ore, that now gives a much better starting material for smithing. More, in order to fulfil the huge demand for blades that lasted for 100 years, swordsmiths mass-produced swords and during about this period, most of them did not use inherited method from ancestors. Therefore, inherited methods from Koto time largely began to go extinct.
Increased transportation facilities made them able to travel and settle wherever they wanted, and smiths thus began to live in castle towns or big cities. Due to this ability to travel and learn, and because of the loss of most of the knowledge of Koto times for the already-mentioned period of mass-producing, they started to mix the older styles, and the old classification of the five sword schools was no more.
Therefore, individual characteristics appeared much more pronounced than before tamahagane was mass-produced in this period, becoming more uniform and of better quality, with less impurity. So even local characteristic of materials are, from this point, no more of help for determining the provenance of a blade. An easy-to-find (but neither definitive nor exclusive) difference between between Koto and Shinto is the boshi shape.
Edo period is divided in five sword periods, the last two being the Shinshinto period:
Keigen-Shinto period (1596 - 1623)
Keigen is a name of an era in Shinto time made by mixing the initial names of the eras Keicho and Genna. Swords made during this period are called Keigen-Shinto. In this period, a lot of tachi made in the Nambokucho period were shortened to adjust the length to about 70cm in order to wear them in the waist as required by the new fighting style (and fashion). The mihaba near the kissaki and nakago is almost same size, and the kissaki is o-Kissaki. This shape became popular, but the difference between Nambokucho blades and Keigen-Shinto is the kasane. Kasane is now thick. These shape will appear again in the end of the Edo period.
The influence of the European culture increased with the increasing of commercial exchanges. Goods were excanged between Europe and Japan in this period, and European iron was also imported. The Japanese name for this iron is nanban-tetsu, "steel of the Southern Barbarians." Smiths begun to proudly sign on the tang of their creatures "made with nanban tetsu" because European items were really fascinating to the Japanese. But Kokan Nagayama quotes in his "Token Kantei Dokuhon" that such a steel wasn't better than tamahagane for making Nihonto due to the impurities in it, especially phosporus. This foreign steel is brighter than Japanese steel, and soon the fashion went out.
Kanbun-Shinto period (1658 -1683)
In this period, the centers of swordmaking were Edo and Osaka, and a new style of sword appeared. This sword has extremely little sori. In 1683, the Tokugawa Shogunate prescribed the maximum size of katana and wakizashi. Therefore, swordsmiths commonly made long swords around 70cm. These two main centers of swordmaking incorporated different features reflecting the different nature of the cities. As Edo was the center of the military power, the Shogunate swordsmiths put emphasis on the sharpness and functionality of the blade, as expected by a military point of view. Shape was functional and hamon wide. The waves of the hamon lowered round the monouchi - that is the part used for cutting and most exposed to shocks. Lowering the hardened part means to leave more softer steel there, allowing better shock-resistance. Kotetsu is the most famous example of the Edo production in this period.
On the other hand, Osaka was the business heart of the nation. As the traders were considered much lower in rank than Samurai in the caste system, we find many more wakizashi made in this school of swordmaking, mostly because traders were forbidden to own a long sword. Nonetheless, this wealthy class began to show their real status by wearing extremely well-made koshirae. Sukehiro is the most famous smith of the Osaka school in this period. As Kotetsu’s blades, his blades are rated as Sai Jo O-Wazamono, the top of the top in cutting ability. Tests were made to fix such a classification, but these tests weren’t performed with Koto blades, considered too valuable to risk them in tameshigiri, so this classification must be taken with a grain of salt. Most swords in this period show yakidashi, and from now on the hamon type called toran-ha becomes in fashion.
Genroku-Shinto period (1684 -1763)
Genroku is believed to be a golden period for art and manufacturing. People (including Samurai) fell into luxurious habits and began to be corrupted. In this time, famous Yoshimune held the eighth Tokugawa Shogunate and acted in order to recover social conditions, especially of the Samurai that were highly-indebted toward the traders class. In 1719, Yoshimune ordered each Daimyo to make a report stating the names of swordsmiths living in his territory. After this, Yoshimune asked the Daimyo to select representative swordsmiths of their territory, and called those smiths to Edo Castle, commanding them to make swords there.
Yoshimune selected the three most excellent swordsmiths and allowed them to engrave aoi-mon (an emblem of Tokugawa family) on their blades. Nothwithstanding Yoshimune's efforts, this period became time of suffering for swordsmiths due to the decreasing martial spirit of the Samurai. At this time, good finances were better than a good fighting ability. Therefore, the demand for swords dropped sharply.
The shape of swords in this period was not as straight as in Kanbun, but they became more curved, and the width near the kissaki was smaller than near the nakago. Swordsmiths, in order to achieve orders, begun to gave full play to their technique on making drawings in the hamon. Mount Fuji, mums on water, and repeated fantasy designs can be found in hamon of this period. These designs were very skillfully-made, but did not achieve the feel of more traditional ones.