No, a katana or any traditional sword is not capable of cutting a bullet in mid-air. The speed, size, and hardness of a bullet make it extremely challenging to intercept or cut with a sword blade.

Bullets fired from firearms travel at high velocities, often exceeding the speed of sound. They are specifically designed to penetrate targets, and their small size and high kinetic energy make them resistant to being cut or severed by a sword blade.

Attempting to cut a bullet with a katana would require exceptional timing, precision, and speed that far surpass the capabilities of human reflexes. It is an impractical and highly dangerous feat to attempt.

When it comes to dealing with bullets or firearm threats, it is crucial to prioritize personal safety, seek cover, and follow appropriate self-defense protocols. This may involve taking shelter, utilizing available cover, or employing other modern self-defense methods specifically designed for dealing with bullets.

Always prioritize safety and follow the laws and regulations of your jurisdiction when considering self-defense options.