He was born to Hosokawa Sumimoto, another renowned samurai of the Muromachi era.
In addition, he feared Motonaga who had got credit and killed him next year.
In 1543, Hosokawa Ujitsuna who was the foster son of Takakuni, raised his armies, and in 1549, Miyoshi Nagayoshi who was a dominant retainer and the first son of Motonaga betrayed Harumoto and took side with Ujitsuna.
Harumoto and Yoshiteru had battled quite hard with Nagayoshi for the power of the Ashikaga shogunate.
The head family of the Hosokawa clan broke down as a result of his death.