With a satchel full off mobile phone recharge cards strapped to his back, he heads to the street corner he calls his "shop", and shouts his voice hoarse until dusk, trying to sell to passersby.
In the evening he jostles with adult commuters for transport home, and then surrenders the day’s takings to his "boss", a woman who buys the recharge cards from a mobile communications company.
"Selling juice-up cards is not a joke," Ziruvi told IRIN. "I am out there in the sun the whole day and sometimes I go home with virtually nothing, on an empty stomach. That means the boss gives me nothing as well, because I am paid on commission." He started hawking three months ago.
His parents encourage him to keep going because it provides the family some much-needed extra income. His father buys fish at a nearby lake and sells it, while his mother is a vegetable vendor.
Ziruvi is among thousands of children below the age of 18 who have quit school and are on the streets trying to help families make ends meet. Education is the last thing on his mind.
"What education are you talking about?" he replied when asked. "I’ll probably go back to school next year when the teachers return. That is, if they return. At the moment the classroom doors are locked."
Zimbabwe’s dwindling band of teachers who have not yet abandoned the profession or left the country, do very little teaching these days; they are protesting what galloping inflation has done to their salaries, and the end-of-year examinations hang in the balance due to industrial action.
Ziruvi has ambitions; his eyes are set on the black market foreign currency trade. "I am confident that one day I will drive one of the latest BMWs on the road. I am planning to get into forex, and then ngoda [diamonds] and possibly fuel."
The problem of working children in Harare was getting worse, the programme coordinator at the Coalition Against Child Labour and Abuse in Zimbabwe, Pascal Masocha, recently told a workshop organised by the Zimbabwe Congress of Trade Unions (ZCTU).
According to the coalition’s research, the number of employed minors – with ages ranging from five to 17 – had jumped from 60 percent in 2007 to 75 percent so far in 2008. HIV and AIDS, the country’s unparalleled economic crisis, the collapse of family support networks as a result of the strain, were all factors driving the increase, said Masocha.
He pointed out that children were not just hustling on the streets – typically selling food items and hawking phone recharge cards – but were also expected to look after elderly or infirm parents.
The problem of child labour is not restricted to Harare; the Child Protection Society (CPS) told IRIN the situation in other parts of the country was "pathetic".
"The year 2008 clearly shows that child labour is on the increase, not only in Harare, but throughout the country. The use of minors in employment that is detrimental to them has reached saddening proportions," said CPS information officer Shemiah Nyaude.
"Basically, the problem emanates from the macro-economic crisis that Zimbabwe is going through. With each year the crisis is deepening, and accompanying that is rising unemployment and, of course, poverty."
For years, an estimated 80 percent of the people have been below the poverty datum line, in an economy marked by the highest inflation rate in the world – now officially at 231 million percent, but unofficially thought to be many times higher – acute shortages of basic commodities, a crumbling health system and the incapacity of government to provide social safety nets.
"Vulnerable household heads cannot access social support from the government, and that leaves children with the burden of having to fend for families. It seems the relevant authorities are burdened with other things, to the extent that they view the curbing of child labour as a luxury," said Nyaude.
Although laws against child labour existed in Zimbabwe, he said municipal authorities and the police were not enforcing them, and blamed companies that "look aside when children are used in the sale of their products".
Nyaude also blamed parents "for exacerbating child labour through the wrongful thinking that children have to go through difficult experiences in order to be equipped for future challenges".
ZCTU’s acting secretary general, Japhet Moyo, said his organisation was "extremely concerned with the extent of child labour" and accused the government of "paying lip service to the problem".
"Children have been left on their own, and it seems that the government thinks that the problem of child labour is confined to the International Labour Organisation and NGOs. Zimbabweans are among the most heavily taxed in the world and one wonders why some of that money cannot go towards social security," Moyo told IRIN.
He said child labour rendered children vulnerable because, left to fend for themselves, they were "particularly prone to self-abuse through drugs and beer, and to abuse by others sexually, psychologically and physically".