Yunus wasn't always a vigilante - he used to be a bricklayer and made a decent wage.
But two years ago, Boko Haram's fighters arrived with their SUVs and AK47s and murdered his father. Two days later, they came to his house in the town of Gwoza in north-east Nigeria, but Yunus (30) escaped. His two sisters were not so lucky.
Like so many other young women in the region, including the Chibok schoolgirls, his siblings were kidnapped by the Islamist extremists, and Yunus believes they were forced to marry the brutal insurgents.
Yunus fled north to the city of Maiduguri, where he resettled in the impoverished urban district of Kaleri.
Maiduguri, in Borno State, was ground zero for Boko Haram and was home to some of the worst atrocities of the seven-year conflict. However, its people were also the first to fight back against the murderous Islamists and today, it remains a safe zone for over a million internally displaced people.
Angry and embittered, Yunus wanted to fight back, so he joined the Civilian Joint Task Force (CJTF) - a community vigilante group based in the city.
"The reason why I joined this vigilante group was as a result of the death of my father and the abduction of my sisters," he says. "I was determined to prevent future events, not only to myself, but also the community. My younger sisters are still under captivity of Boko Haram."
Dressed in bright red top and blue jeans, Yunus doesn't look like a fighter. He is tall, thin and softly spoken.
But Yunus is also angry and, like 23,000 other men who joined the CJTF, he wants to win back his country and way of life.
The CJTF has been an important tool in the fight against Boko Haram. Armed with knives, sticks and torches, units, like the one Yunus commands live in the communities where they root out insurgents and hand the suspects over to the military.
He explains: "When I joined the CJTF initially, there were people in possession of ammunition, members of Boko Haram living there. The community was afraid to identify them.
"Now that the situation has become calm, when we see these people, we identify them and hand them over to the military forces. We have caught more than 10 people who are Boko Haram members."
Asked how they find suspects, he explains: "We target them in the middle of the night. We go to their house. We catch them and we take possession of their ammunition to start making use of it in the community."
In their communities, the CJTF have been praised for their work. Yunus and the 15 men in his unit are paid a small allowance by local elders and get some training, but are generally poorly funded.
The CJTF was a useful tool in the fight against Boko Haram and politicians have also commended the bravery of the men. However, it has become a monster that the government and military is struggling to control.
Video evidence, uncovered by some NGOs, shows members of the CJTF and the military torturing and murdering Boko Haram suspects without trial. One member even boasted in an interview that he had found a "foolproof" way to kill up to 50 insurgents. He described putting the Islamists in a pit, pouring in kerosene and then setting it on fire.
Borno state governor Kashim Shettima described the CJTF as "more dangerous than Boko Haram". He said they risked becoming "Nigeria's Frankenstein".
Wearing a balaclava to hide his identity, Yunus hit back: "The government has used our work and then they withdrew their support. The government has not been there for the families of our members who were killed."
The Nigerian government has recently declared victory over Boko Haram. In December, the military captured the last rebel stronghold in the Sambisa Forest. Last month, it negotiated the return of 82 of the kidnapped Chibok girls - though around 113 remain in captivity.
Yunus concedes that the day where the CJTF is no longer needed may be close, but he has no plans to go back to laying bricks. "I would like to be a soldier," he says.
His chances of getting into the military are slim, however. There are an estimated 23,000 members of the CJTF, with many hoping to transition into the military or police. However, in the last round of army recruitment, just 300 were selected.
The fallout from the conflict has been devastating. Some towns have seen their working male population either wiped out or coerced into joining Boko Haram. It has meant that farming and food production activities have stalled, resulting in malnutrition and, in places, famine. Some small villages report having no children under the age of five.
Girls, kidnapped and turned into "wives", are escaping and returning to their families. But many are treated like pariahs. Some fathers believe their daughters, many of whom have borne children as a result of rape, bring shame on the family.
Paul O'Brien, CEO of the charity Plan International Ireland, said that because there were so many crises going on in the world, including those in Syria and East Africa, this area "feels forgotten". But he said: "It is one of the worst I have come across, not in terms of the sights you see, but more in terms of the stories you hear."
Mr O'Brien said he was particularly affected by the abduction of young people."Boys to be soldiers for Boko Haram, the girls, essentially, to be married off as child brides.
"I don't think we have ever come across a crisis where that deliberately happened."