Jubei Jimushi is a memorable member of the Kouga Manjidani clan, recognizable at once by his extraordinary and unsettling physical form. He is essentially a living torso, lacking all four limbs, which gives him the appearance of a writhing serpent or a crawling insect. Despite this, he is far from helpless. He has long, flowing black hair, pointed ears, and a scar across his right eye, often with a strip of metal worn across his nose and cheeks. He wears a pale yellow tunic with large grey shoulder pads, and his most striking features are his unnaturally long, snake-like tongue and his ability to move at high speeds by flexing his chest muscles to manipulate armor plates sewn onto his clothing. His very existence is a testament to the genetic consequences of centuries of selective inbreeding among the ninja clans, which produced warriors with incredible powers but also with significant physical abnormalities.

In terms of personality, Jubei is a composed and highly intelligent individual who remains calm even in the most perilous situations. He is acutely aware of his physical disadvantages in combat, a reality he has adapted to with cunning and a unique fighting style. He is not prone to idle conversation or revealing more than necessary. This is best demonstrated by his refusal to tell his fellow clansmen about a dark prophecy he foresaw regarding the future of his clan's leader, Gennosuke, and his desire to marry Oboro from the rival Iga clan. Jubei saw sorrow and loss in that future path, but he understood that Gennosuke would not change his mind, so he chose to let fate unfold without causing unnecessary alarm. This stoic and pragmatic wisdom marks him as one of the more level-headed members of the Kouga.

Jubei's role in the story begins when he sees a dark star portending danger over his clan's elder, Danjo. He sets out in a palanquin to investigate, a journey that leads to his direct confrontation with the Iga clan. He is intercepted by the powerful Iga ninja Tenzen Yakushiji and his allies, who are shocked by his limbless form. However, Jubei displays no fear. He initially appears to kill Tenzen by surprise, using his hidden blade to stab him through the chest. This act underscores his deadliness and his ability to leverage an opponent's underestimation of him. Later, he encounters the dying Kouga ninja Shogen Kazamachi, who throws the sacred scroll listing the combatants to Jubei. Jubei catches the scroll in his mouth, but his escape is cut short when he is confronted once more by Tenzen, who somehow survived the fatal blow. In a final desperate attack, Jubei projects his hidden blade at Tenzen with his tongue, but the Iga ninja, now aware of the trick, easily slices him in half mid-air.

Jubei's key relationships are primarily with his Kouga comrades. His skill as a fortune-teller makes him a consulted figure within the clan, as seen when he warns Shogen of danger near water, a prophecy that tragically comes true. He shares a moment of quiet tension with the ninja Hyoma Muroga, who questions him about Kagerou's distress after Jubei refused to tell her the fate of Gennosuke. This interaction highlights his role as a keeper of difficult truths. His primary adversary is Tenzen Yakushiji. Their encounter is a pivotal moment that demonstrates both of their abilities: Jubei's lethal surprise attack initially succeeds, only to be rendered meaningless by Tenzen's own mysterious resilience, leading to Jubei's own demise.

The character's development is brief, given his early exit from the conflict, but it is impactful. He is introduced as a mysterious soothsayer, quickly proves himself a formidable and clever fighter, and then falls victim to a power he could not have anticipated. His arc powerfully illustrates the brutal and unpredictable nature of the ninja war, where even a successful killing blow does not guarantee survival. Similarly, his fate shows that his prized ability to read the stars did not grant him the power to change his own destiny.

Jubei's notable abilities are as unique as his appearance. His primary physical skill is his snake-like locomotion, allowing him to slither across the ground at speeds that outrun other ninja on foot. His most ingenious combat technique involves a hidden blade, a short sword kept concealed within his own throat. Using his extraordinarily long and prehensile tongue, he can draw this blade out to strike at an opponent in a sudden, unpredictable attack, then return it to its sheath and swallow it again. Beyond these physical tactics, Jubei possesses the genuine supernatural power of fortune-telling. By reading the stars, he can predict future events with unerring accuracy, a skill his clansmen trust implicitly. His predictions, which include Shogen's misfortune by water and Tenzen's ill-fated luck, are always correct, establishing him as a genuine seer within the story's world.