Orochimaru, one of the main antagonists in the "Naruto" series, is often depicted with a sword in his mouth. The sword is known as the Kusanagi Sword.

The reason Orochimaru holds the sword in his mouth is primarily a stylistic choice and a representation of his unique and eccentric personality. It is an artistic portrayal meant to emphasize Orochimaru's unorthodox nature and his ability to execute surprise attacks.

The sword in Orochimaru's mouth allows for quick and unexpected sword strikes, catching opponents off guard. By holding the sword in such a manner, Orochimaru can maintain the element of surprise and take advantage of his opponents' momentary distraction or underestimation.

In terms of the storyline, the Kusanagi Sword holds significance as a legendary weapon associated with Japanese mythology. Orochimaru possesses a deep interest in acquiring powerful artifacts and techniques, and the Kusanagi Sword is one of those prized possessions.

In summary, the sword in Orochimaru's mouth serves both as a representation of his character's unique traits and as a visual representation of his ability to execute swift and unexpected attacks.