Lifespan: Eishō 14 (1517) to Tenbun 16 (1547)
Clan: Date → Kasai
Father: Date Tanemune
Adoptive Father: Kasai Tanekiyo
Siblings: Yakata Gozen (wife of Sōma Akitane), sister (formal wife of Ashina Moriuji), Date Harumune, Ōsaki Yoshinobu, Date Sanemoto, Date Genbamaru, sister (wife of Nikaidō Teruyuki), sister (wife of Tamura Takaaki), Munezumi, sister (wife of Kakeda Toshimune), Koori Munesada, Kasai Harukiyo, Yanagawa Munekiyo, Murata Munetane, Gokurakuin Sōei, Watari Tsunamune, Watari Motomune, Ōari Yasuura, Shichirō, Kosugō Gozen (wife of Sōma Yoshitane)
Kasai Harukiyo served as a daimyō during the Sengoku period.
In 1517, Harukiyo was born as the son of Date Tanemune, the sengoku daimyō and fourteenth head of the Date clan of Mutsu Province.
Harukiyo became an heir of the Kasai clan of Mutsu, and, upon the sudden death of his adoptive father, Kasai Tanekiyo, inherited the headship of the Kasai clan through the authority of the Date notwithstanding heightened feelings of opposition toward the Date among members of the Kasai family.
Before long, a conflict between Date Tanemune and his son, Date Harumune, erupted in an event known as the Tenbun Conflict. Harukiyo sided with his father, Tanemune, and engaged in ongoing territorial disputes with his uncle, Kasai Harutane, who sided with Harumune in the dispute with Tanemune.
Harukiyo died in Tenbun 16 (1547).