Kusanagi, also known as Kusanagi-no-Tsurugi, is a legendary Japanese sword with significant mythological and historical significance. It is one of the Three Imperial Regalia of Japan, along with the Yata no Kagami (the Sacred Mirror) and the Yasakani no Magatama (the Sacred Jewel).

According to Japanese mythology, Kusanagi was discovered inside the body of an eight-headed serpent by the storm god Susanoo, who gifted it to the sun goddess Amaterasu as a reconciliation gesture. Amaterasu then entrusted the sword to her descendant, Emperor Jimmu, who became the first emperor of Japan.

As a mythical sword, the specific design and characteristics of Kusanagi vary in different legends and artistic depictions. However, it is commonly described as a straight, double-edged sword with a slightly curved tip. The blade is said to possess exceptional sharpness and mystical powers.

Kusanagi is considered a symbol of imperial authority and is associated with Japanese royalty. The sword is housed at the Atsuta Shrine in Nagoya, Japan, where it is regarded as a national treasure. The actual physical form of Kusanagi is not publicly accessible, and it is rarely seen by the public.

It's important to note that Kusanagi is a legendary and mythological sword, and its existence as a physical artifact is a matter of mythology and belief.