One of them infected Tori, Kazuto's older sister.
Thanks to the channeling of energy and self-isolation that Kazuto did for his sister, Tori had maintained her sanity much longer than the others.
Victims infected with this virus will suffer from shortness of breath, and their sanity will slowly disappear. Once they lost their mind, their bodies would turn into frightening monsters called Windigo. These Windigoes would attack whatever was the target of their first sight.
Once a Windigo has set someone as its target, the monster will chase until it eats all its prey meat without caring for other prey nearby.
After consuming its first prey, this WIndigo would target other prey and kills other monsters that block its path.
When this outbreak first occurred in the Wolf Clan, many victims died, and corpses were scattered everywhere.
Unfortunately, once a person turns into a Windigo and loses his identity, that person could never return. The only thing that could stop this massacre is to kill all Windigoes.
However, this Windigo could not be killed with Elemental powers or ordinary weapons. The one who could kill it is a magician or magic-user, and one of them is Kazuto.
At that time, Tori was still pregnant with Tora when she had symptoms of turning into a monster. Kazuto immediately rushed his sister to a place that was more quiet and calm while channeling his energy to slow down his sister's transformation.
He succeeded, and Tori gave birth to Tora safely, and Tora grew very well.
They could last for five years even after the deadly virus outbreak has ended thanks to the purification and refinement carried out by the wizards of the Ace force.
The only thing left was Tori, who could infect anyone close to her. Kazuto hid this fact not to let the Ace kill his sister and isolated Tori in a remote area near the wolf clan border. He did not allow other clans to come near, but Tora, his only nephew.
Maybe because Tori conceived Tora, so that child didn't catch on the virus or anything. Also, the immune system of young children is much stronger than that of adults.
Kazuto felt even more confident when he realized that all the victims who caught the virus and turned into monsters were adults. Young children were not infected at all, no matter how long they approach the infected victims.
That's why he doesn't have to worry about Tora catching this virus, and almost every day takes the boy to meet his mother.
However, no matter how much effort Kazuto put into healing his sister, Tori's health took a turn for the worse.
Tori knew that there was a risk that Kazuto had to pay every time he channeled his energy to suppress the transformation on her. Every time Kazuto finished directing his life energy into her, Kazuto would always vomit blood, and his body would go limp for several hours.
At first, Kazuto only needed to channel his energy once a week, so Tori didn't mind receiving an energy transfusion from her brother.
But as time goes by, the virus in Tori's body gets stronger and insists on controlling her mind and turning her into a Windigo. As a result, Kazuto had to channel his energy at least once every two or three days.
And now… after five years since Tora's birth, the time needed is getting narrower, which is every few hours. This makes Kazuto unable to go on missions and has to stay here with her.
Tori felt she had taken away her brother's freedom and she hated being a burden to someone, especially for the younger sibling she loved the most.
That's why Tori decided to end both her and Kazuto's suffering. She purposely didn't tell Kazuto that her body was slowly changing. She covered her ears with her long hair and wouldn't speak open her mouth in front of her brother so that Kazuto wouldn't see her sharpened teeth.
Until one day, Tori felt that the time was getting closer and she wouldn't be able to maintain her sanity. Tori decided to cook her brother's favorite soup and enjoy her last day to the fullest.
Then she confessed to her brother that she couldn't stand it and decided to give up. Unfortunately, Kazuto became angry and didn't want to listen to her at all.
Tori decided not to yield and said what she had always wanted to tell her brother.
"I want you to promise me. If I lose control and change in front of Tora, I want you to kill me with your own hands."
Tori knew there were only a few hours left before she finally turned into a vicious Windigo. Tori wanted her brother to see that she wanted to die at the hands of his brother rather than at a wizard she didn't know.
She didn't want to change in front of her son and make Tora the main target in her sight once she turned into a monster. She knew she was feeling selfish by letting Tora be by her side.
What power does she have? She is a mother, and there is no place she wants to be but to see her son smile at her.
Tori wanted to spend the rest of her life with her son… with her younger brother… Only then could she die in peace.
"Sister. You're crazy. I. won't. ever. kill. you. " Kazuto replied firmly, emphasizing each word in his last sentence.
Not having had time to get a response from Tori, Kazuto heard a very gripping howl, making his body tensed.
"Go. Our clan members need you. "
And so, Kazuto went to help his clan, which was attacked by another beast clan, leaving Tori alone with Tora, while Tori's time was not long.