Chokuto / Tang Dao, were very early style swords from both Japan & China. Even the early samurai used straight sword such as this.
The traditional Japanese sword is a folded sword. Just one type of steel is folded preserving the integrity of the steel. Traditional folded swords have a fine grain pattern, which is subtle, like a fingerprint in the steel. Originally, this folding technique was to distribute the carbon content evenly as possible throughout the steel. Also it was a way of ridding impurities from the steel. This practice is one of the reasons why the original Japanese swords are so honoured for their quality. In modern times this practice is more of a formality due to the fact the steel from the modern age mills is already so pure and precise.
Our Chokuto here has just that a folded blade. With a brilliant polish. It is also clay tempered, another famous technique pioneered by the Japanese.
Clay tempering is an art, as well as a science. The traditional clay tempering techniques are perhaps the pinnacle of Japanese sword design and construction. Not only is the natural temper-line, the "hamon" a beautiful sight, open to artistic design, and interpretation like a painting. It also serves a very functional purpose. The resulting clay tempering process produces a hard edge, while the body remains slightly softer. This means that the edge is more resilient to dulling, and it is very sharp. While the body is able to flex whilst cutting targets, allowing for great exertion on the blade without breaking it. A clever engineering technique from medieval Japan.