Lifespan: Unknown to 10/22 of Tenbun 8 (1539)
Title: Assistant Captain of Imperial Guards of the Left Division
Clan: Kira (Later Period Tōjō-Kira (Shimo-Kira))
Father: Kira Mochikiyo
Siblings: Mochihiro, Arakawa Yoshihiro
Wife: Seto-no-Ōfusa (daughter of Matsudaira Nobutada)
Children: Nishio Yoshitsugu, daughter (wife of Kira Yoshiyasu)
Adopted Heir: Yoshiyasu (second son of Kira Yoshitaka)
Kira Mochihiro served as a bushō during the Sengoku period. Mochihiro was the seventh head of the Later Period Tōjō-Kira clan and the lord of Tōjō Castle in Mikawa Province.
Upon the outbreak of the Ōnin-Bunmei War, Mochihiro’s grandfather, Kira Yoshifuji, joined the Western Army of Yamana Sōzen. Originally, the Saijō-Kira clan with whom the Tōjō-Kira engaged in frequent disputes allied with the Eastern Army of Hosokawa Katsumoto so the two Kira clans battled against each other in their territory in Mikawa. While the confrontation between the two clans persisted into the Sengoku period, Mochihiro was born as the son of Kira Mochikiyo, the sixth head of the Tōjō-Kira. Around the time of Mochihiro, the Tōjō-Kira clan approached the Imagawa clan (the sengoku daimyō of Suruga and Tōtōmi provinces) as a counterbalance to the goodwill that the Saijō-Kira clan cultivated with the Oda clan of Owari Province. The Tōjō-Kira clan also established ties with the Matsudaira clan of Mikawa who were in conflict with the Oda as a means to stand-up against the Oda.
In 1535, Mochihiro offered protection to Matsudaira Hirotada, the heir to the main branch of the Matsudaira family, after Hirotada was ousted from his base at Okazaki Castle owing to an internal conflict. Mochihiro invited Hirotada to his territory in Ise Province and mediated support for the Matsudaira from Imagawa Yoshimoto. In 1536, for Hirotada’s return to Mikawa, Mochihiro’s chief retainer (Tominaga Tadayasu) invited him to Muro Castle in the Hazu District. This was a step toward his return to Okazaki Castle the following year. Mochihiro attended the event for the crowning of Hirotada with a traditional cap at Hirotada’s coming-of-age ceremony. Hirotada also received one of the characters in his name from Mochihiro.
Amid concerns of military threats posed by Oda Nobuhide of neighboring Owari Province, in 1539, Mochihiro died. He was succeeded by Kira Yoshiyasu, the second son of Kira Yoshitaka of the rival Saijō-Kira clan and an adopted heir. However, there appeared some resistance to this succession. In the family history of Nishio Yoshitsugu, the founder of the Yokosuka domain in Tōtōmi, Mochihiro adopted Yoshiyasu because his natural son, Yoshitsugu, was an infant sent to Owari as a hostage of the Oda and grew-up there. Later, Yoshiyasu’s older brother, Yoshisato, was killed in battle against the Imagawa, so, after inheriting the Tōjō-Kira clan, Yoshiyasu also took control of the Saijō-Kira clan. Although Mochihiro had a natural son, the adoption of Yoshiyasu offered a means to reconcile with the Saijō-Kira clan.