Katanas are not banned in Japan; however, their possession and sale are subject to strict regulations under the Sword and Firearms Control Law (刀砲刀剣類所持等取締法, Tōhō Tōkenrui Shoji-tō Torishimari Hō).

In Japan, owning and possessing certain types of swords, including katanas, is allowed, but it requires appropriate licensing and registration. The law classifies swords based on their historical or cultural significance. Genuine antique swords that hold historical value, such as those recognized as Important Cultural Properties or National Treasures, are generally permitted for possession and sale.

However, the possession of non-traditional swords, replica swords, or modern-made swords without significant historical value may be restricted or prohibited under the law.

To legally possess a katana in Japan, individuals, both Japanese citizens and foreigners, need to follow specific procedures and obtain the necessary permits. This typically involves acquiring a sword possession permit (To-ken Menkyo or To-ken Tōroku) from licensed dealers or the Japanese government authorities.

It's important to note that the regulations and requirements for owning and acquiring katanas can vary based on factors such as the type of sword, its age, and other criteria. To ensure compliance with the regulations and to obtain accurate and up-to-date information, it is advisable to consult with Japanese government authorities, such as the local police or the Agency for Cultural Affairs. They can provide guidance on the possession and sale of katanas and help navigate the legal procedures and permits required.