Saiken, also known as the Six-Tails, is a fictional character from the anime series Naruto. It is one of the nine Tailed Beasts, a massive slug-like creature that resides within Utakata, its jinchūriki. Saiken possesses immense power and the ability to produce corrosive substances, which it uses to defend its host and itself. In the series, Saiken plays a crucial role during the Fourth Great Ninja War, where it is captured and later released. Its character adds depth to the ongoing battle between the shinobi and the Tailed Beasts.