Katanas are not banned in Japan. While there are regulations in place to control the possession and trade of certain types of swords, including katanas, under the Japanese Sword and Firearms Control Law (Sword Law), they are not outright banned.

The regulations aim to protect the cultural heritage associated with traditional Japanese swords, including katanas, and prevent their unauthorized trade or export. The Sword Law requires individuals in Japan to obtain a certification, known as a "sword license" or "sword possession permit," to legally possess and trade Nihonto, which includes katanas. These licenses are issued by the prefectural police and require individuals to meet specific criteria, such as age, background checks, and membership in a recognized sword-collecting organization.

The regulations surrounding Japanese swords in Japan are primarily in place to preserve the integrity and historical significance of traditional swords and prevent their misuse or illegal trade. They are not intended to ban the ownership or possession of katanas outright.

It's important to note that laws and regulations regarding swords can vary in different countries and jurisdictions. If you have specific questions about the regulations governing katanas in a particular location, it's best to consult the local laws or seek legal advice to ensure accurate information.