Kakei Masashige served as a bushō during the Sengoku and Azuchi-Momoyama periods. He was a retainer of the Matsudaira (Tokugawa) clan in Mikawa Province.
Masashige was born as the son of Kakei Masaharu, a retainer of the Matsudaira clan. Masashige, together with his older brother, Kakei Shigetada, served Matsudaira Kiyoyasu and Matsudaira Hirotada (father and son), the lords of Okazaki Castle. In 1547, he received orders to assassinate Matsudaira Tadamichi, the lord of Kamiwada Castle in Mikawa. Masashige then headed with Shigetada toward Kamiwada, and after pretending to submit to Tadamichi, took Tadamichi’s head while he was asleep. He then assisted his brother to withdraw from Kamiwada and together they returned to Okazaki.
After the demise of Hirotada in 1549, Masashige served his son, Matsudaira Motoyasu (later known as Tokugawa Ieyasu). In 1556, when the Oda clan of Owari Province assaulted Ukigai Castle defended by Sakai Tadatsugu, Masashige joined with reinforcements in the defense of the castle. In the fifth month of 1560, during the Battle of Okehazama, Masashige, along with Shigetada and his younger brother, Kaki Masanori, joined in an assault against Marune fortress.
In 1563, during the Mikawa Ikkō-ikki, Masashige joined the Shōman Temple in opposition to Ieyasu. During a battle in Azukizaka that same year, Masashige engaged in a spear fight against Hiraiwa Chikayoshi, injuring his opponent. He then deployed for the Battle of Kamiwada against Matsudaira forces. When scouts were sent to the Shōman Temple, he decimated them and together with Watanabe Moritsuna killed a scout named Fuse Yoshitsugu.
After suppression of the uprising, Masashige came under the command of Ōsuga Yasutaka. In 1569, during the Siege of Kakegawa Castle defended by Imagawa Ujizane, Masashige fought against enemy reinforcements at Kaketsuka. In 1576, after Yasutaka entered Yokosuka Castle, Masashige served as a lieutenant-general in a battle against the Takeda clan. Thereafter, he served as a military commander for Yasutaka. In 1590, during the Conquest of Odawara, Masashige affiliated with the division of Ōsuga Tadamasa (the heir of Yasutaka). Masashige’s son, Kakei Masanaga, became a retainer of the Mito domain of Hitachi Province.