Saizo is one of the Ten Heroes of Sanada and a legendary warrior from medieval Japan. He is the most recognized, along with Sarutobi Sasuke.
In the anime, Samurai Deeper Kyo, the Lord Yukimura is protected by the Ten Heroes of Sanada (based on the Ten Heroes themselves). Kirigakure Saizo is one of the more distinct members, along with Sarutobi Sasuke.
The name Kirigakure also appears in Naruto as the name for the Village Hidden in the Mist, or Hidden in Mist for short.