Lifespan: Daiei 5 (1525) to Tenshō 12 (1584)
Title: Director of the Bureau of Military Storehouses
Lord: Ōtomo Yoshishige (Sōrin) → Ryūzōji Takanobu
Father: Kuroki Akitaka (under one theory, this is the same individual as Ienaga)
Siblings: Ienaga, Kamachi Masutane
Children: Nobezane, daughter
Kuroki Ienaga served as a bushō during the Sengoku and Azuchi-Momoyama periods. Ienaga was the lord of Nekoo Castle in the Kamitsuma District of Chikugo Province.
The Kuroki were kokujin, or provincial landowners, based in the township of Kuroki at the convergence of the Hoshino and Yabe rivers near the central portion of the Kamitsuma District in Chikugo. The Kuroki were counted among a group of fifteen influential families located in Chikugo under the command of the Ōtomo referred to as the Fifteen Castles of Chikugo. Ienaga’s father (Kuroki Akitaka), his grandfather (Kuroki Akizane), and his great-grandfather (Kuroki Chikazane), all received one of the characters in their names from the head of the Ōtomo clan of Bungo Province. Consequently, it appears that, over these generations, the Kuroki served the Ōtomo. Ienaga, however, initially opposed Ōtonmo Yoshishige (Sōrin) and did not receive one of the characters in his name from Yoshishige.
In 1564, as a large contingent from the Ōtomo army came to attack his base at Nekoo Castle, Ienaga intercepted them with a comparatively small force. Despite holding-out for a while, he could not overcome the superior numbers fielded by the Ōtomo and, along with Kuroki Sanetsura and others, surrendered. Thereafter, he pledged allegiance to the Ōtomo and served in numerous battles. In 1578, at the Battle of Mimikawa, after the Ōtomo suffered a bitter defeat to the Shimazu of Satsuma Province, the influence of the Ōtomo in Chikugo waned. Meanwhile, the Ryūzōji clan of Hizen Province gained influence. As a result, Ienaga was compelled to submit to the Ryūzōji.
In the fifth month of 1581, Ryūzōji Takanobu murdered Kamachi Shigetsura, the lord of Yanagawa Castle, and slaughtered his family. Further, he killed in battle Ienaga’s younger brother, Kamachi Masutane, at Kamafunatsu Castle in Yanagawa. Enraged at the deeds committed by the Ryūzōji, Ienaga rebelled against them and was then surrounded by forces led by Ryūzōji Masaie and Nabeshima Naoshige. Owing to mediation by the Kusano clan (kokujin based in Hizen), the two sides settled on the condition that Ienaga tender his lineal heir as a hostage to the Ryūzōji.
In 1584, after the death in battle of Ryūzōjhi Takanobu at the Battle of Okitanawate, Ienaga sent a written pledge to the Ryūzōji vowing that he did not have any intention to rebel, but this major defeat suffered by the Ryūzōji provided an opportunity for the Ōtomo to invade their territory. The fact that the Kuroki clan earlier switched their allegiance from the Ōtomo to the Ryūzōji made them an attractive target for the Ōtomo army who proceeded to lay siege to Nekoo Castle. Shiga Chikatsugu, a retainer of the Ōtomo, participated in this siege. In response, the Kuroki forces called upon the Ryūzōji to send reinforcements and made a robust defense, resulting in a stalemate with the besieging forces. Nevertheless, after Tachibana Dōsetsu and Takahashi Jōun rushed forward to reinforce the Ōtomo, the reinforcements from the Ryūzōji fell after a violent clash with the Tachibana forces. Meanwhile, the provisions in the castle began to run low, causing Ienaga to give-up the resistance. On the condition that the lives of his subordinates and family be spared, he committed seppuku, dying at the age of sixty.
At this time, Ienaga is said to have been beheaded by his thirteen-year-old daughter. In regard to the circumstances of his death, there is one theory that he took his own life upon surrender and, under another theory, he was initially pardoned but later killed after exhibiting signs of rebellion.