Tunu is a small hyena cub, with grey fur and dark grey markings on his back and forehead. His paws and muzzle are also this color. His nose is black and his eyes are blue. His tail is dark grey with a light pink fur underneath. This light pink color is also present on his underbelly. He also has one small tooth sticking out of his mouth.
Like his sister, Tunu is a very shy hyena cub who is afraid of all lions from both the Outlands and Pride Lands, even after Kion exerts warmth towards them. He is shown to be very playful, often following his sister everywhere.
But over time, he learned to overcome some of his fear of lions and, by his next meeting with Kion, feels safe enough to even extend his thanks.
Tunu and his sister, Wema are engaged in a playful staredown with Madoa. He notices his fellow clan member, Jasiri walking towards them with Kion in tow. Tunu runs after his sister and the pair hide behind a nearby stone. After Kion eventually notices them he tries to greet them and coax them out, but they back down in fear. Madao reveals that all they have ever known are bad lions, hence his apprehension. She then explains the need for their watering hole to be returned to the young ones in particular. Tunu watches Kion leave from a distance.Later, the Lion Guard are able to reclaim their watering hole. With their watering hole is returned to them, Tunu and Wema are once again playing together. When Wema notices Kion she runs over to him, with Tunu following her close behind. Noticing the two youngsters, Kion tries once again to reach out to them, believing them to be unafraid of him now. But after taking a swift glance towards each other, the pair once again hide behind a nearby rock. Jasiri tells Kion to take it as a compliment because he really is fierce after all.
Tunu and Wema are happily playing together when Jasiri pounces on them. Upon realizing that it's her, they start to laugh happily, before going off in search of Madoa. As they are searching, Janja and his clan appear nearby. With Jasiri distracted, Cheezi and Chungu chase after Tunu and Wema and the youngsters cry out for Jasiri to help them. She arrives and pushes the pair of hyenas away, but Janja then tackles Tunu, Wema, and Jasiri into an open vent. With Jasiri unable to climb back out, the group has no choice but to wait for help. Madoa, noticing this from nearby, leaves to get the Lion Guard.
When the Guard arrives, they quickly begin to take down Janja's clan, while Jasiri constantly tries to assure Tunu and Wema that they'll be okay. Bunga suggests using the Roar until he's reminded that it will blow the cubs away as well. Eventually, Kion orders Beshte to use a large rock nearby to help them. Beshte knocks the rock down to the ground and warns Jasiri of the incoming splash. She shields the cubs from the lava and, when close enough, the three hop onto the still rising platform. With the other hyenas abandoning their leader, Tunu, Wema, and Jasiri join the Lion Guard's stand against Janja. He soon leaves, not wishing to fight all of them. Jasiri then thanks the Lion Guard for their help, though is still a bit concerned at how ruthless Janja had been, though Kion chalks it up to it being the Dry Season. Deciding that it's time to leave, Jasiri takes the cubs back home, with both thanking the Lion Guard before they leave.