No, a katana or any traditional sword is not capable of cutting through a bullet. Bullets are small, high-velocity projectiles designed to penetrate targets, and they are made of materials that are much harder than the blade of a sword.

The speed, force, and hardness of a bullet make it highly resistant to being cut or severed by a sword blade. When a bullet impacts a solid object, it is designed to penetrate or pass through it, including metal, wood, or other materials. The sword blade, while sharp and strong, is not designed to withstand or cut through the bullet's casing or core.

Attempting to cut a bullet with a sword would be extremely dangerous and ineffective. The bullet's momentum and kinetic energy would likely overcome the strength and structure of the blade, potentially causing severe injury or death to the wielder.

When it comes to dealing with bullets or firearm threats, it is important to prioritize personal safety, seek cover, and follow appropriate self-defense protocols, which may involve seeking shelter or employing other modern self-defense methods.

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