The newly born baby was without a home. His house was burned down and his family killed by unknown assassins for who they were. A family with an ability to become animals slaughtered because they were different; cursed. A woman stumbled upon the baby and adopted it as her own, though her husband was not so happy about it. The husband vowed that as soon as the baby could uphold itself, it was to be out of the house. The woman regrettably agreed and took the baby to the extra room in the house. As she laid the baby down to sleep, she decided the baby need a name.
"Kio," She said. "I'll call you Kio. And you will be my Kio."
By 10, Kio wasn't much of the baby he once was. He had grown to be an intelligent, talented boy. He had taken a liking to electronics and technology and had become the electrician of the house. His studies of the electronic world never seemed to end as the days went by. As he studied electronics, he developed numerous techniques to using his talent with electronics for his own good.
One day, a man arrived at Kio's home. He wandered about the house and slaughtered Kio's adoptive family. When the man finally made it to Kio's room, he only smiled at him.
"Don't worry, boy. This'll only take a second." He said. Kio became enraged. His body shook with anger, and his senses became enhanced. As his body shook more, it filled with heat and began to cover with hair. He fell to his knees as his bones cracked and reshaped themselves into a whole new shape: a wolf.
Growling, the black and grey wolf inched closer to the mysterious man. The mysterious man stared in awe at the wolf as he backed away. The wolf began to bark and strut closer to the man as the hairs on its back began to rise. Finally, the man turned and bolted out of the house, never to return.
After a few days of wandering about the house and hunting, the wolf finally transformed back into Kio, the lovable 15-year-old boy. As he put his pants on, he vowed to himself not to ever get attached to another person again—otherwise they will just get killed like the others.
Three years later, Kio is a full-fledged shinobi for Sunagokure. His squad gains word of a house being caught on fire and two women were missing. Immediately, the squad goes into action. First, they found the burnt house. Searching around the black ashes of the once house and found the dark corpse of an old woman. Unhappy, Kio begins to sniff the house and transform into a wolf. He begins to follow the scent of what he hopes to be the other woman. After hours of hunting, Kio comes across a young girl lying on the ground. Carefully, he sniffs her and licks her face in hopes of her awaking. When she doesn't, he transforms into his human form and picks her up.
"You're safe, now." He said, taking her to a hospital back in Sunagokure.
Unconscious for days, the girl finally awoke on a most unfortunate of days: it was raining in Sunagokure. Quickly, Kio learned that the girl was afraid of rain. She attempted to run out of the room when she woke up, but he luckily caught her.
"Nope. You're staying here." He said, smiling at her. The girl looked up at him and then at his chest and focused all of her might into one punch into Kio's chest. He chuckled and kneeled down to stand at her height.
"What's your name?" Kio asked. The girl stared at him for a second, not saying anything.
"Well, I'm Kio, and from the looks of it, you're going to need a place to stay."
Over the next year, the girl stayed with Kio. During the entire year, she remained nameless. One evening, like the one when she awoke, it was raining. The girl clung to Kio's chest, shaking and thrashing.
"Hey, calm down. It's just raining."
"No, no, no." She said, thrashing more.
"Firagun, stop it." Kio said. The girl stopped in mid-thrash and stared at him.
"What did you call me?"
"Firagun. It suits you. Do you not like it?" Kio asked.
"… I love it."
After that, the two became inseparable. Their care for each other became love and both of them followed each other to keep each other company. Kio could barely be happier with Firagun, always following her whenever he could. He considered himself to be the one to take care of her and make her okay whenever she needed him. She became everything to him. No one could mean more anything more to him than she.