He is the great-great-grandson of Shiro and Yamabuki, the great-grandson of Riki and Fuji, the grandson of one of Gin's siblings, the son of Kinumaru and Billy, the grandnephew of Gin, the nephew of Joe, Weed and Yukimura and the second cousin of Bellatrix, Kōshirō, Orion, Rigel and Sirius.
He is a white Akita Inu mix, with circles over his eyes sharing his family birthmark and has blue eyes. Shion greatly resemblances his great-great grandfather Shiro.
Shion is known to be brave when defending those he cares about and resourceful being able to take care of himself.
Like Weed and Sirius, he is calm, polite and friendly. He looks up to and admires his granduncle Gin wishing to meet him.
Through his friendship with the bears in Nagano and Niigata, he understands that not all bears are bad but not all are good either.
He's a good teacher, as seen by teaching Chibi the language of dogs meaning he is patient, and he is also playful with the young bear cub.
However, he doesn't appreciate reckless and dangerous acts like Sirius not getting out of the way of a rockslide.
Shion is first seen in the road holding a piece of bread, and is hit by the family Sugarwara's car but is unharmed by the impact. The human boy Kenta grows attached to the little white dog, and brings Shion and his mother Kinumaru food every day.
One day Kenta's bullies realize where he's going and goes to beat him up. Kenta tells Shion and Kinumaru to run, but Shion defends Kenta from the bullies.
It is revealed that Shion had a father named Billy that suddenly disappeared causing the death of his 8 siblings. Later on, Kinumaru also dies, leaving Shion alone. One day the bullies get a dog named Rad that fights Shion.
Shion wins this fight making Kenta brave and stick up to his bullies. When Shion sees Kenta's potential he disappears. At the end of the story, Shion is shown to be able to survive on his own, as he's seen looking for food in garbage cans.
Shion is inside an abandoned wooden hut, when Gennai Ogasawara and his comrades barge in. Shion introduces himself and explains that he got his name from human children. The following morning, Shion and Gennai travel down the mountain until they come across a river with a wooden bridge.
Gennai notices something in the water and upon inspection, it turns out to be a dead boar caught on the posts of the bridge. The dogs haul it out of the water and begin eating. Later that day, Rocket and Kyōshirō tell them about the threat of the bears and how serious it is.
When Gennai discusses it with them, Shion tells him that he is, in fact, the grandson of Gin's brother, and came to Ōu, in order to find his great-uncle and discover his roots.
Shion runs off to find his family and Gennai chases after him. He finds Shion climbing up a tall cliff side and upon arriving at the top he loses sight of him. Shion has made his way through the woods and has found the prison where the Ou dogs are being kept. A small bear is sat on top of the rocks and notices Shion approaching, instead of attacking, Shion greets the bear.
The bear attacks Shion, but he is spared from death by Gennai who attacks the bear himself, getting lightly wounded in the process. More bears arrive to help their brother but with the arrival of Kenshin, Bob, and Shirozaru, the bears flee leaving the dogs behind.
Shortly after, Rigel and Sirius arrive with Kawasemi, and the dogs become reacquainted with each other. However, the sound of howling echoes ominously throughout the forest, and the dogs flee in case the bears come back.
Shion and the group find Monsoon attacking Kenshin, and after the bear kills two of his followers and badly wounds Kenshin, Shion runs forward and speaks with the bears directly, confusing Bob and the bears themselves. Monsoon and Shion continue to protest to each other, but before the dogs can escape, Monsoon pounces for them.
Sirius tell Shion to listen to him, he say okay. Sirius has Shion tell Monsoon that he is a representative of the Ohu Army. But Monsoon has Shion ask Sirius if he has authority of a leader like Riki and Gin. Shion talks to Monsoon in Bear Language and tells Sirius what Monsoon said and if Sirius remembers about Monsoon's conditions that the dogs are his food.
Just as he was about to watch his cousin, Sirius about to be killed he was saved by Daisuke and Hidetoshi and along with the others he watches the bears flee. Then, he sees his injured comrades get taken away for treatment, Shion and Rigel are asked by Sirius to follow him so they can find Monsoon. He tries to talk with Bob and tell him that Monsoon gave the order to flee, but Bob tells him that Monsoon will come back. After hearing the story of Monsoon's hatred for the Ohu Army.
He sees his cousin Orion and the others come out of the woods, Shion watches as his cousins Orion and Sirius argue about what to do about Monsoon. Then, just as the two brothers were about to fight they were stopped by Andy.
Even though, the fight between Orion and his brother Sirius was broken up by Andy the opposing views still placed a gap between them. Then, Shion and the others saw Akame collapsed from exhaustion and heard from him that he wanted Orion to take the sickle. When Sirius tries to take it he gets pinned by Rigel and with that Orion calls it the last straw, to everyone's shock he disowns Sirius as his brother.
Still at Futago Pass, Shion continues to watch the argument between Sirius and Orion until Yamabiko broke up the fight. Then, heard the arrival of their allies and was asked by Sirius to translate that the bears had to run, but Shion says those bears are evil and they are not like the bears he knows, and if they don't deal with them now they will attack his cousins' friends again.
When Sirius asks him to come up and translate Shion knew it was still dangerous but Sirius assured him it was okay, but was stopped by Orion. Shion, together with Orion and the others, watches Sirius try to talk to the bears but he looks on with horror as his cousin was about to get struck, but thanks to the hunters he was saved.
With all of Monsoon's Kin dead, but Akame has fallen and quickly revived as the rest of the dogs watch him and Izō leave. Shion leaves Sirius with to fill out the kishu's request without saying goodbye since Bob couldn't go Shion was the only one who could speak bear.
Sirius still wants to talk to Monsoon, he and Sirius are stopped by Bob and the dog tells them that Monsoon isn't someone they can reason with. Using himself as an example convincing them not to go and asks why would a bear lend it's ears to a dog,the akitas just say Bob is speaking with energy now because Monsoon isn't here and would do the opposite if he were here. But he still considers them blind to the truthand Sirius considers that's the reason why Bob won't trust them. Shion listens to Sirius tell Bob that Monsoon has given up on him and that he's free to live the rest of his life in paradise as long as he doesn't cause any trouble. With that said they quickly leave but are stopped by Gennai but they quickly run past him following Monsoon's scent.
Finally, Shion is seen with Sirius entering Monsoon's territory looking for him. They find Monsoon at the top of the waterfall but when they try to talk to him. The white Akita tells Sirius that Monsoon still looks angry and throws a rock at them but Shion sees that Sirius isn't going to give up yet.
The two continued the search for Monsoon all the way into nightfall and they find a cave behind the waterfall for them to hide in. But upon being in the cave Sirius and Shion discover that Bob uses the cave to escape the torture of Monsoon when Shion asks why Sirius is doing this all the akita can say is that everyone Monsoon cared about was killed right before his eyes understanding the bear's grudge against dogs. But he also doesn't want Monsoon to hurt others and Shion says we're only food to him; Sirius says that the only reason Monsoon sees them as food is because of his grudge.
When morning comes, Sirius and Shion sense Monsoon's presence on the other side of the cave but Sirius tells Shion not to go out there as they see his claws come through the cave.
They try to move further back into the cave but it's no use, Monsoon finds them but Sirius and Shion escape under the water but Shion can't swim and his brought to shore by Sirius. Seeing that Monsoon is having another one of his tantrums the two flee by climbing the waterfall.
As Shion and Sirius continue their persute Monsoon lashes out at the pair again destroying the forest in the process refusing to listen to the dogs he tries to talk Monsoon out of revenge but it was no use because he tells them that his only goal was to eat all the dogs. He gives them another condition if they give up their friends as food, then he won't kill the dogs at random; but says he'll never negotiate with them and leaves.
After that Shion starts to see the hopelessness of the situation saying to his cousin that Monsoon isn't the kind of enemy they can talk to and that they should go back. Sirius corrects him saying that Monsoon just talked to them now and wishes to continue.
The two have been tracking Monsoon for days but have a hard finding his scent since it was so strong. Then, he asks Sirius why does he want to get along with Monsoon he reminds his cousin if they fight him directly both sides will be in danger but even if they could stop the fighting Monsoon couldn't be trusted.
Then, they see a group of hunting dogs, Shion notices that the dogs belong forest watchmen but understanding the danger they're in the two leaves to warn them.
Shion and Sirius make it to the hunting dogs and humans to warn them about Monsoon but they are approached by the dog's owner. But as soon as the dogs got Monsoon's they dashed after him with Shion and his cousin telling they don't stand a chance. He is pushed by Sirius to keep up and says that he is doing his best but tells Sirius to go on ahead.
Seeing what Monsoon had done Shion tells him that the humans will take revenge against him and that he'll die in his home. Before the last hunting dog is killed Shion manages to distract him and Sirius gets her to but Shion is surprised that Monsoon remembered Sirius's name, and dives into the bushes. He points out to his cousin Sirius what happened and he hears Sirius saying they are on the first step of a breakthrough.
Shion and the others hide while Monsoon continues to look for them but then they hear Gennai and his group close by.
Shion watches Sirius trying to stop Gennai but all he says is that we're nothing but food to him with Monsoon's claws coming down Gennai pushes Sirius out of the way. When he sees Monsoon puts his paw on top of Sirius knocking him out Shion attacks him and when Sirius comes too he gets a hug from Akakama. Then, Shion and the others notice a helicopter and begin to assume that the humans have spotted Monsoon.
Then, Shion hears Sirius remind them again that he to talk to Monsoon not fight and Andy says it's okay to risk his life but not Shion's but he said he was alright with it. Just as he was about to run off with Sirius to find Monsoon again they hear a cry for help and find Paulie and with Sirius's mind made up Shion continues with his cousin. He begins to see the helicopter return and hides in the bushes understanding that Monsoon won't come out with humans around. Shion and Sirius notice Gennai's group leading the helicopter to Monsoon suspecting that they are following them and shocked they won't listen.
They continue to watch Gennai's group from afar until they leave. By night fall, they hear a scream to discover that it's Monsoon who killed his own kind a mother bear and now was prepared to kill the cub. Shion asks Monsoon why he killed the mother bear and he's is that the cub wasn't of our bloodline. Asked by Sirius to convinced Monsoon to let the cub go and he starts to believe that Monsoon is a monster. Then, watches Sirius leap on the bear's back he calls out that's too dangerous then Shion rushes to his cousin's side when Sirius gets thrown off but doesn't get flatten by the bear. Shion sees Rigel and the Kamakiri brothers coming and Monsoon starting to get angry.
Despite his best to calm Monsoon the bear flew into a rage but they escape with the cub into tow. He sees that his cousin and the brothers still here but after hearing his cousin's reasoning he watches the trio leave. When morning comes Shion asks Sirius what are they going to do with the cub he hears that cub will stay with them until he comes independent. Sometime later, he and Sirius help the bear cub make a grave for his mother the cub was heartbroken that he cried until he fell asleep. Once the cub awoke Shion had the idea of teaching him dog language in doing so they give him the name Chibi.
Seeing that Chibi wasn't safe, Shion and Sirius take him to Rigel and the others. Shion watches Rigel accept Sirius' pleads, and agrees on taking Chibi back with them to Ōu. Shion assures the cub that he will take Sirius back with them later.
Continuing the search for Monsoon Shion gets told by Sirius that he doesn't like to be formal and will not his cousin's playing around. They smell the bear's scent all over but have a hard time finding him soon the pups notice a rock slide heading straight for them Shion and Sirius get out the way and suspect it was Monsoon's doing. Upon seeing him he tells the bear that he wants to play right and it will be more fun if we play together. As the rock slide continues Shion warns Sirius to get out of the way if he doesn't want to die but all Sirius does is stand there begging the bear to wait. With a rock heading straight for Sirius he pulls him out of the way calling him an idiot.
Then, he gives Sirius a stern scolding for being reckless that when he says he's giving up but gets told by Sirius to lend his voice to Monsoon. Even though, he knows it's not the right time he says to Monsoon what he was doing was dangerous and they are the only ones willing to stand up for him. When Monsoon walks away Shion seeing how dangerous this is believes it's no use to continue until Sirius says otherwise. He hears the Kamakiri brothers and finds them over the next ledge. Upon meeting them he hears Kurokama mention of Gennai's battle plan.
After being informed of the brothers support for Sirius he pretends along with him to save Monsoon. Then, he sees his cousin being cared away by Monsoon and told by the others to follow him. After finding them he is seen by Gennai and the Kamakiri brothers swimming with Sirius and Monsoon until the bear pulls him under the water and saves him. Upon hearing humans he is told by Sirius to hurry and reunites with him but when he sees Monsoon's treatment of his cousin he is unsure and warns him if anything happens to Sirius the Ohu Army will come after him. After Sirius's playful attempt, Shion tried to tell Monsoon it was a joke but the bear flies into a rage soon after Gennai and the others arrive he sees Sirius fly into a rage himself over them breaking his promise.