Lifespan: 15xx to 8/16 of Tenshō 15 (1587)
Title: Governor of Sagami
Lord: Aso Koremasa → Aso Koretane
Father: Kai Chikanao (Sōun)
Siblings: Chikahide, Nobushige, Naotake, sister (wife of Kumanoshō Morimasa), sister (wife of Hayakawa Kyūun), sister (wife of the lord of Izu-Noyama Castle)
Children: Daughter (wife of Kiyama Jōtaku)
Kai Chikahide served as a bushō during the Azuchi-Momoyama period. He was a retainer of the Aso clan in Higo Province in Kyūshū.
Chikahide was born as the eldest son of Kai Chikanobu (later known as Sōun). He received one of the characters from the name of Sakanashi Tsugumoto and adopted the childhood name was Tsugukazu. After entering the priesthood, he adopted the name of Sōritsu. He held the title of Governor of Sagami.
Acting in opposition to the diplomatic policies of their father, Sōun, Chikahide’s three younger brothers attempted to establish relations with Itō Yoshisuke of Hyūga Province, after which Sōun killed all of them upon suspicion of plotting a rebellion. Chikahide then sought to oust Sōun, but failed. As the only surviving heir to the Kai clan, Chikahide’s life was spared through the intervention of retainers. According to one theory, this incident was the reason for the poisoning of Sōun by Chikahide’s wife. After the death of Sōun, Chikahide became the chief retainer of the Aso clan, but he did not abide by the will of Sōun to stay in place to defend the base of the Aso clan at Yabe. Instead, in 1585, he attacked Hananoyama Castle (aligned with the Shimazu clan, inviting a counterattack.
After the Shimazu forces toppled Kōsa and Kashida castles, Chikahide abandoned his base at Mifune Castle. He then vacated Kumanoshō Castle and surrendered, but was apprehended during the settlement negotiations and taken to Yatsushiro. After the surrender of Aso Koremitsu, the two-year-old head of the Aso clan, to the Shimazu, Koremitsu was taken by his mother who fled, marking the end of the Aso clan.
Before long, Kyūshū was subjugated by Toyotomi Hideyoshi, and Chikahide recovered his former territory of Mifune. The kokujin, or provincial landowners, however, opposed the policies of Sassa Narimasa who was dispatched by Hideyoshi to serve as the lord of Higo. This led, in the eighth month of 1587, to the Higo Kokujin Uprising. Chikahide devised a plan with Kikuchi Takekuni as the commanding general to attack Kumamoto Castle with 35,000 kunishū, or local forces, but, just before the fall of the castle, his forces were repelled. In the end, the rebellion was suppressed and Takekuni killed in action. Chikahide fled but was located at the Kengun Shrine by forces under Mori Katsunobu, a yoriki, or security official, of Narimasa. Rather than place himself in the hands of the irregular forces, he entered the Jizō Temple in the village of Rokkasho and killed himself.
As noted, his three younger brothers were murdered by his father, so the death of Chikahide resulted in the end of the Kai clan. Sōun’s killing of three of his own sons led to the eventual elimination of the Kai clan.
The Kai Shrine in Kashima in the Kamimashiki District of Higo is known as the Ashiketō Shrine. As reflected in its name, those who pray there can seek to recover from arm and leg ailments. After incurring injuries to his legs and arms during the Higo Kokujin Uprising, Chikahide received special treatment from local residents. To express thanks for the care received, he said that after his death a shrine would be built to protect those with ailments of the arms and legs. His father, Sōun, is also prayed for at this shrine.