Lifespan: 15xx to 16xx
Title: Shimōsa-no-kami (honorary)
Lord: Nasu clan
Father: Iono Sukemune
Siblings: Sukenobu, Naokiyo, Odagiri Naohisa
Wife: Daughter of Sakuyama Nobutaka
Children: Sukeshige, Suketomo, Sukeyoshi
Iono Sukenobu served as a bushō during the Sengoku and Azuchi-Momoyama periods. He was a retainer of the Nasu clan. Sukenobu served as the twentieth head of the Iono clan and as the lord of Iono Castle in Shimotsuke Province. The Iono were one of the key clans serving the Nasu known as the Seven Clans of the Nasu.
On 9/17 of Tenbun 18 (1549), Sukenobu participated in the Battle of Kitsuregawa-Sōmezaka. In this battle, Nasu Takasuke led 300 soldiers to invade the territory of the Utsunomiya. As a result, upon orders from Ashikaga Haruuji, the Koga kubō, Utsunomiya Hisatsuna led an army of 2,500 men to deploy to the Kitsure River and engage in battle against the Nasu forces.
Initially, the Utsunomiya enjoyed an advantage based on their superior numbers, so Takasuke used troops lying in ambush in Sōtomezaka to create havoc for the Utsunomiya army, reversing the tide of the battle in favor of the Nasu. Takō Nagatomo (a retainer of the Utsunomiya), Michikawa Tadachika (a retainer of the Kasama), and the Yokota brothers (five sons of Yokota Tsunamura who were retainers of the Yokota) fought valiantly, halting the assault by the Nasu army, but Tadachika and the Yokota brothers were killed in action. These individuals are known as the Five Brothers of the Yokota.
In 1590, during the Conquest of Odawara, despite deploying late, Sukenobu still received recognition of his rights to his landholdings of 740 koku. Beginning in 1592, he joined in the Bunroku Campaign on the Korean Peninsula, serving under the command of Katō Kiyomasa. He fought valiantly at the Siege of Ulsan and was praised by Kiyomasa and Asano Nagamasa.
In 1600, at the Battle of Sekigahara, Sukenobu served in the Eastern Army to defend against Uesugi Kagekatsu. On 9/14, when the Uesugi forces attacked Iono Castle, he clashed with and repelled the attackers on Mount Seki. After the war, for his contributions, he received an increase to his fief of 2,000 koku in Takanezawa; however, owing to injuries sustained in battle, his eldest son, Iono Sukeshige, died of illness so his second son, Iono Suketomo, became the lineal heir and inherited the Iono clan in a group of hatamoto led by the Nasu serving on behalf of the Edo bakufu.