Yes, the Japanese did have straight swords in their historical weaponry, although they were not as prevalent as curved swords like the katana. Straight swords were used in earlier periods of Japanese history before the development and widespread adoption of the curved blades.

One example of a straight sword used in Japan is the chokutō, which was the predecessor to the curved swords like the tachi and later the katana. The chokutō had a straight, double-edged blade and was primarily used during the Kofun and Asuka periods in Japan (from the 3rd to 7th centuries).

As Japanese swordsmithing techniques and martial traditions evolved, the preference shifted towards curved blades. The introduction of the tachi, a longer and more curved sword, marked the transition from straight to curved blades. The tachi eventually gave way to the katana, which became the iconic sword of the samurai.

The curved design of the katana offered advantages in cutting and slicing, as well as in the overall balance and handling of the sword. It became the preferred weapon due to its effectiveness in combat and its significance within samurai culture.

While straight swords were not as prominent in later periods, they still held historical and cultural significance. They were used in ceremonial contexts, as symbols of authority or rank, or as part of traditional practices in martial arts or theater performances.

In summary, while the Japanese primarily used curved swords like the katana, they did have straight swords in earlier periods of their history. The shift towards curved blades reflected advancements in swordsmithing techniques and martial traditions, and the curved swords became the iconic and widely recognized symbols of Japanese sword craftsmanship.