Whether you can walk around with a katana depends on the laws and regulations of the jurisdiction in which you are located. In many places, carrying a katana in public is likely to be illegal or heavily regulated due to its classification as a weapon.

In the United States, laws about carrying bladed weapons such as katanas vary from state to state. Some states and cities have restrictions on the length of a blade that can be carried in public, while others may have specific regulations on carrying swords or other bladed weapons. It is generally not a good idea to walk around with a katana in public, as it could lead to legal issues or be perceived as a threat by others.

In the United Kingdom, carrying a katana in public without a valid reason is illegal. The Criminal Justice Act 1988 prohibits the possession of an offensive weapon in a public place without lawful authority or reasonable excuse. A katana would likely be considered an offensive weapon under this law.

In other countries, similar restrictions often apply. It's important to research local laws and regulations regarding the public possession and display of weapons, including katanas.

If you are participating in a historical reenactment, martial arts demonstration, or other activities that require a katana, make sure to follow any relevant laws or guidelines and consider using a transportation case or bag to carry the sword when not in use. Always exercise caution and prioritize the safety of yourself and others when handling any weapon, even if it is blunt or intended for display purposes.