Jasiri is a fairly small and slim spotted hyena, though she displays strength when fighting Janja's clan. She has gray fur that bears a slight purplish tint. Her lower legs and paws are a very dark shade of purple, and her underbelly is a dull pinkish orange. Her tail is short and bicolored; most of it is deep purple like her paws, but the fur on the very bottom is much paler, the same color as her underbelly. Her eyebrows and ears both match the color of her mane and paws, and her inner ears are dull pink. On each side, she has three round spots, slightly darker than her main coat color, lined up vertically from her shoulder to the joint of her foreleg. Two smaller spots fleck her face on either side, and she has darker stripes along her neck as well as a streak along her spine. Her muzzle is the same color as her spots. She has large, deep blue eyes, encircled by darker fur, and a dark purple mane that is striped with brighter purple. Her mane is long and thick, with a lock in the front drooping to one side.
Jasiri is a friendly and communicative hyena whose personality is the opposite of Janja and his clan. Jasiri understands and respects the Circle of Life, whereas Janja's clan of hyenas only care about themselves. Jasiri even goes so far as to teach Kion himself a few points about the Circle of Life that he previously didn't understand. However, her ties to her species shines through in how often she laughs, and even Kion notes that the world is like a giant game to her. She is very determined, adventurous, courageous, fearless, brave, spunky, vivacious, effervescent, and lively, so she has been described by her voice actor as zany and opinionated. She is shown to be a bit provocative, teasing, and sassy, not to mention confident in her fighting skills. Her bravery is displayed when she takes on Janja's entire clan. She is often territorial, antisocial, and reclusive, but this seems to be a cover for her rather thoughtful side.
Whilst Jasiri shows loyalty, her mind is not free of dissuasion. This is shown by how she was eventually led to believe Zira's lies about Kion's true intentions. But when doubt plagues her mind, she can become frustrated with herself should her doubts be revealed as the truth.
When Kion gets separated from the rest of the Lion Guard, he finds himself lost in the Outlands where he meets Jasiri, a friendly female hyena who has been spying on him since he first entered her territory. Jasiri introduces herself and informs Kion that he is going to wrong way to Flat Ridge Rock, his desired location to meet up with the Guard. She tells him the correct direction. However, Kion ignores her, not willing to trust a hyena, and continues in the direction he was headed. Jasiri, amused, follows him.
Along the way, Kion becomes tangled in a thorny bush after ignoring Jasiri's advice. Whilst Kion fears for the worst, Jasiri helps him out, amused at his accident. She then shows him the right way to Flat Ridge Rock, but soon notices that Kion is limping. Believing it to be partially her own fault, she decides to walk with him until his foot is healed. A short while later, they witness the Circle of Life in action when a chameleon snaps up a nearby fly. She becomes offended at Kion after he insinuates that she and all hyenas have no idea how the Circle of Life works. She then talks to Kion, explaining the hyenas' role in the Circle of Life when he reveals that he does not believe that any hyenas follow it. Jasiri sings "We're the Same (Sisi Ni Sawa)", with Kion eventually joining in, and he soon discovers how alike they truly are.
Soon they arrive close enough to Flat Ridge Rock for the two to part ways. However, shortly after Kion leaves the Outlands, Jasiri is confronted by Janja, Cheezi, Chungu, and the rest of their clan. She begins to fight each of them one on one, and manages on her own for a while. Janja gets tired of Jasiri "playing around" and quickly pounces on her, pinning her to the ground. Before Janja can do Jasiri any harm, Kion returns to save her, knocking Janja aside in the process. The fight continues until Kion and Jasiri are backed into a corner. Kion tells Jasiri to stay back, and she watches as he uses the Roar of the Elders to send Janja and his clan packing.
The roar alerts the rest of the Lion Guard, who come rushing to Kion's aid. When Fuli sees Jasiri, she begins to growl, ready to strike the hyena. Kion explains that Jasiri is a friend, which causes confusion from Bunga, who whispers to Kion that she's a "hyena". Jasiri is equally surprised that Kion regards her as his friend. Kion tells the Guard about Jasiri's ferocity in battle with Janja's clan and how not all hyenas are bad. The Guard soon accepts Jasiri, claiming that any friend of Kion's is a friend of theirs. Jasiri and Kion then part ways as trusting friends.
Jasiri goes to the Pride Lands, where she finds Bunga and greets him. Kion arrives, and Jasiri informs him that she needs his help back in the Outlands. She explains that some lions have taken over her clan's watering hole and won't share it. They are surprised to hear that lions are causing trouble, but Jasiri assures them that she knows what a lion looks like. Kion decides to go to the Outlands to solve the problem, and Jasiri thanks him, then hopes that everything is a misunderstanding.
On the way, Jasiri voices her initial doubts that Kion would help her, as this time the antagonists are lions, unlike their last encounter. Kion is still confident that the lions aren't being intentionally harmful, and Jasiri agrees that it took time for the pair of them to trust each other. They reach Jasiri's clan, where Jasiri introduces Kion to her sister Madoa. Jasiri notes that they all need the water, so Kion quickly leads her forward. He's telling her that lions are reasonable when Nuka pounces on her, angrily ordering her away.
Kion comes to her rescue, and Jasiri stands by his side when Nuka, joined now by Kovu, threatens him. She informs the two lions that Kion's father is Simba, which causes them to take Jasiri and Kion to their mother, Zira. Jasiri crouches and glares at Zira as she approaches, but does not hesitate to tell the lioness that she brought Kion to the Outlands, and that Kion is her friend. Zira declares that she underestimated Jasiri, as she did not know Jasiri was friends with royalty, and Jasiri adds that Kion is the leader of the Lion Guard. She is confused when Zira suggests Kion use his Roar to give her water, and looks beseechingly at her friend. She watches in awe as Kion roars at a cloud, producing a brief rainstorm.
Jasiri asks if he knew of this power, and he denies. When asked, Zira states that she feels uncomfortable talking about the Roar in front of a hyena, to which Jasiri snaps that she just wants her watering hole back. In an undertone, she tells Kion that she doesn't trust Zira, but hopes that he will be able to convince her to share the water. Zira takes Kion for a talk, giving Nuka the opportunity to growl at Jasiri. Zira orders her son to play nice, and Jasiri bites at Nuka, startling him. She laughs and mockingly agrees to play nice.
As they wait for Zira and Kion to return, Nuka becomes impatient and charges at Jasiri. Kovu intervenes and points out that Zira told them to be kind, but Jasiri laughs again and assures "Green-Eyes" not to worry, confidently pronouncing that she can play any game that Nuka wants to play better than he can. Nuka makes to attack Jasiri, but Zira arrives, causing Nuka to hold Jasiri close and claim that they were just playing nice. Jasiri moves away, causing him to fall, and asks where Kion is. Zira says that they've reached an agreement; the watering hole belongs only to lions. Jasiri professes that Kion would never agree to such a thing, but Zira aggressively commands her to leave. Jasiri reluctantly complies.
Dejectedly, Jasiri is heading back to her clan. She runs into the rest of the Lion Guard, to her surprise, and inquires what they're doing. They tell her that they're looking for Kion, and she notifies them that he's joined Zira. They recognize the name, and, when asked by Jasiri, assert that Kion would want no part of her doings. Jasiri is not shocked by this, realizing that she should never have believed Zira's words. She returns to Kion, who is surrounded by the Outsider lions, with the Guard. Laughing, she exclaims "Surprise!" as the group rushes to their friend's defense. She chases an Outsider lioness, grinning and snapping at her tail.
Back at the watering hole with her clan, Madoa reveals that she's glad Jasiri has Kion for a friend. Jasiri adds that she's glad to have all the Lion Guard as friends, and Fuli agrees. Wema and Tunu approach Kion, then flee, but Jasiri assures him to take it as a compliment to his ferocity.
Two hyenas at Disney's Animal Kingdom, Scooter and Zawati, possibly served as inspiration for Jasiri. These hyenas were introduced to the writers of The Lion Guard by Jill Mellen, who made the suggestion of a friendly hyena to the writers of the show.