Yes, you can bring a samurai sword from Japan to the United States, but there are specific procedures and regulations you must follow.

1. Export from Japan: In Japan, swords that are considered nihonto (traditional Japanese swords) are national treasures. To legally export a nihonto from Japan, you must obtain a permit from the Agency for Cultural Affairs in Japan. The sword must also be inspected to confirm it was made using traditional methods.
2. Transportation: Swords are generally not allowed in carry-on luggage on airplanes due to safety reasons. You should pack the sword in your checked baggage, and it should be securely wrapped and sheathed to prevent injury to baggage handlers and inspectors.
3. Import to the United States: When you arrive in the United States, you must declare the sword at customs. There are no specific restrictions on importing a samurai sword into the United States, but customs officials will likely want to inspect it to ensure it complies with any relevant laws and regulations.
4. State and Local Laws: Once in the United States, you must comply with any relevant state and local laws regarding the possession, display, or sale of the sword. Laws can vary widely from state to state and city to city, so it's important to check the specific regulations in your area.

Remember, laws and regulations can change, so it's always best to check for the most current information in your specific situation. If you're unsure about any part of the process, it could be helpful to consult with a legal professional or a customs broker.