Kimotsuki Kaneyuki served as a bushi during the Azuchi-Momoyama and early Edo periods. He was the twentieth and last head of the main branch of the Kimotsuki clan of Ōsumi Province.
In 1592, Kaneyuki was born as the eldest son of Kimotsuki Kanemori, the nineteenth head of the clan.
Around this time, the Kimotsuki were ousted from their former territory at Kōyama Castle in Ōsumi and transferred to Satsuma Province. Owing to internal conflicts with the band of retainers and a divorce from his wife (the second daughter of Kimotsuki Yoshikane), Kaneyuki’s father, Kanemori, was censured and his landholdings reduced to 100 koku. Thereafter, in 1600, at the Battle of Sekigahara, Kanemori was killed in action. Kaneyuki then inherited the headship of the clan at the age of nine.
In 1611, when Shimazu Iehisa brought Emperor Shōnei from the Ryūkyū Islands to Kyōto, Kaneyuki accompanied the party in his capacity as a retainer of the Shimazu. During the return, the boat on which he rode encountered stormy weather and was wrecked, at which time he drowned. He was twenty years old.
At the time, Kaneyuki was not married and did not have an heir. He did not have any siblings either, so, with the death of Kaneyuki, the bloodline of the main branch of the Kimotsuki clan was extinguished.