Yanagimoto Jinjirō served as a bushi and retainer of Hosokawa Harumoto. Jinjirō also served as lord of Sanjō Castle in Kyōto.
Jinjirō’s father, Yanagimoto Kataharu, cooperated with Hosokawa Harumoto to defeat Hosokawa Takakuni. He became a member of Harumoto’s newly established administration, but he often conflicted with Miyoshi Motonaga. Kataharu died in the midst of a battle against Uragami Muramune, whereupon Jinjirō succeeded him as head of the family.
After killing Takakuni at the Daimotsu kuzure, or the Collapse in Daimotsu, Motonaga came into opposition with retainers of Harumoto including Kizawa Nagamasa. Early in 1532, he led forces against Jinjirō at his home base of Sanjō Castle in Kyōto. The castle fell while Jinjirō perished in the battle.
The killing of Jinjirō raised tensions between Motonaga and Harumoto. Hosokawa Mochitaka of the Awa-Hosokawa family served as a mediator. A settlement was reached after Motonaga and his retainer underwent the rite of tonsure and demonstrated their allegiance. Thereafter, Mochitaka severed ties with Harumoto and returned to Awa. The confrontation flared again, whereupon Harumoto killed Motonaga.