Jirobay, more commonly known as Yajirobe, is a recurring character in the Dragon Ball Z narrative. He is a ronin, a masterless samurai, who first encountered Goku during his youth while Goku was pursuing one of King Piccolo's demons. At the time of their first meeting, Yajirobe proved to be one of the few people who could match a young Goku in combat. His background is that of a mountain hunter with an enormous appetite for food, which is one of his most defining and consistent traits.

Yajirobe's personality is a study in contrasts that makes him a unique member of the Z Fighters. On the surface, he is portrayed as asocial, grumpy, and primarily concerned with his own comfort. He dislikes being bothered by others, especially when he is eating, and often comes across as rude or dismissive. He has a strong love for large meals, particularly roasted wild pig and steamed pork buns. He is often characterized as a coward because he goes out of his way to avoid major conflicts, preferring to watch from a safe distance rather than engage in life-threatening battles. Yajirobe views this not as cowardice, but as being intelligently careful, choosing to conserve his energy while others wear down the enemy. He enjoys simple pleasures like fishing, hunting, and taking afternoon naps, and according to supplementary materials, he even has a habit of driving stolen cars. Despite these lazy and seemingly selfish qualities, Yajirobe possesses a hidden noble side that emerges during critical moments. When Goku is left near death after his first battle with King Piccolo, Yajirobe rushes to help him regain consciousness and carries the severely injured Saiyan to the top of Korin Tower, a feat of strength and endurance that even impressed the divine cat Korin. This act of loyalty, driven by a promise of food, proves pivotal.

His motivations are rarely heroic in a traditional sense. He does not seek to protect the Earth out of a sense of duty or a desire for justice. Instead, his actions are driven by a combination of self-preservation, a strange sense of honor, and an expectation of reward, usually in the form of a large meal. He steps in to fight when he feels threatened or when a promise of food has been made. This pragmatic and somewhat selfish motivation makes his moments of bravery all the more surprising and impactful, as they go against his established nature.

Yajirobe's role in Dragon Ball Z is small but undeniably crucial. He spends most of his time living atop Korin Tower, acting as a hermit and companion to the feline deity Korin. In this role, he becomes the primary caretaker and deliverer of Senzu Beans, the miraculous healing beans that restore a fighter's health and energy. On several key occasions, he is the one who delivers these beans to the wounded heroes, allowing them to continue their battles. However, his most significant contribution comes during the battle against the Saiyan Prince Vegeta. As the other Z Fighters lie defeated, Yajirobe, who had been hiding and watching the fight, seizes a critical opportunity. He uses his katana to sever the tail of Vegeta, who had transformed into a Great Ape, reverting the prince to his normal state and saving Goku from being crushed. Later, when Vegeta attempts to kill the young Gohan, Yajirobe risks his own life to slash Vegeta across the back. While this does not defeat Vegeta, the distraction gives Gohan the moment he needs to transform into a Great Ape himself, ultimately turning the tide of the battle. This single act of courage cements Yajirobe's value to the team.

Key relationships define Yajirobe's place in the world. His most significant bond is with Korin, with whom he shares a long-term, grumpy, but comfortable cohabitation on Korin Tower. Yajirobe acts as a foil to Korin's wisdom, and their dynamic is often a source of comic relief. He also has a deep respect for Goku, who is one of the few people who has earned his loyalty. While he often complains about the trouble Goku brings, he has repeatedly put himself in harm's way to save his life. He maintains a connection with the other Z Fighters, such as Krillin, but mostly serves as a peripheral figure who delivers supplies rather than fighting alongside them.

While Yajirobe does not undergo a significant character transformation, there is a subtle development in his role. He starts as a wandering, self-serving swordsman who can match Goku in combat. Over time, as the power levels of the main villains and heroes escalate far beyond his own, he wisely steps back from direct confrontation, accepting his niche as a support character. He does not pursue intense training or learn to fly or use energy-based techniques. Instead, he hones his role as the supplier of Senzu Beans and a reluctant, last-minute hero. This acceptance of his limitations shows a form of wisdom, as he remains alive and useful while many powerful fighters are killed.

Despite his lack of formal energy attacks or the ability to fly, Yajirobe possesses notable abilities. He is exceptionally strong and swift for a human of his size, as demonstrated when he easily climbed Korin Tower with an injured Goku on his back. His primary skill is his incredible swordsmanship; he is a master of the iaido, or quick-draw, technique. His blade is remarkably sharp, capable of slicing through even the durable armor of a Saiyan warrior. His power level during the Saiyan conflict was recorded at 970, making him stronger than many of his companions at the time, even though he lacks their flashy techniques. His fighting style is simple and direct but brutally effective, relying on his physical strength and the sharpness of his katana rather than ki manipulation.