The use of swords by Japanese soldiers historically had several reasons and evolved over time. Here are some key factors:

1. Historical Tradition: The use of swords in Japan dates back centuries and has been deeply rooted in the country's culture and martial traditions. Samurai warriors, who were highly regarded in feudal Japan, were renowned for their mastery of the sword. Swords held significant cultural and symbolic importance in Japanese society.
2. Close Combat: Swords were effective weapons for close-quarter combat, particularly in situations where soldiers were engaged in hand-to-hand combat or facing opponents at close range. The curved blades of Japanese swords, such as the katana, provided advantages in slashing and thrusting attacks.
3. Status Symbol: The possession and skillful use of a sword symbolized the social status and honor of the samurai class. Carrying a sword was a mark of authority and served as a visual representation of one's martial prowess and noble heritage.
4. Martial Philosophy: The samurai adhered to a code of conduct known as bushido, which emphasized virtues such as loyalty, honor, and discipline. Mastery of the sword was considered an essential aspect of a samurai's identity and commitment to their martial ideals.
5. Transition to Firearms: With the introduction of firearms in Japan during the 16th century, the role of swords in warfare gradually diminished. However, even as firearms became more prevalent, swords continued to be carried by samurai as secondary weapons and symbols of their social standing and heritage.

It's important to note that the use of swords in combat evolved over time, and their prominence varied depending on the historical period and the specific context of warfare in Japan. The cultural significance and martial traditions associated with swords played a significant role in their continued use by Japanese soldiers.