What is Tengagoken in Japanese Katana terminology?

"Tengagoken" (天下五剣) refers to the five famous swords: Onimaru Kunitsuna, Mikazuki Munechika, Dojigiri Yasutsuna, Ootenta Mitsuyo, and Juzumaru Tsunetsugu. Among these, Mikazuki Munechika, Dojigiri Yasutsuna, and Ootenta Mitsuyo have been designated as National Treasures, while Juzumaru Tsunetsugu has been designated as an Important Cultural Property. Onimaru Kunitsuna, on the other hand, is a private property of the Imperial Family, known as ""Gyobutsu"" (御物).

These five swords, with their unique characteristics and historical significance, represent the pinnacle of Japanese sword making. The fact that three of them have been designated as National Treasures underscores their cultural and historical value. The designation of Juzumaru Tsunetsugu as an Important Cultural Property reflects its importance in the cultural heritage of Japan. The status of Onimaru Kunitsuna as a private property of the Imperial Family adds to its prestige and exclusivity."