The teen appeared in Papakura District Court on Thursday afternoon where Judge Jane Lovell-Smith said he would be remanded in custody until he could appear before the High Court on May 23.
Counties Manukau South area commander Inspector Dave Glossop confirmed to the Herald that police were investigating the death.
Glossop said police were supporting the victim's family who were not in New Zealand.
The alleged assault was captured on CCTV and happened in front of a number of shoppers.
Glossop said he could not comment further as the matter was before the courts.
"We are deeply saddened by this tragic loss of one of our team," Countdown managing director Dave Chambers said.
"No New Zealander should go to work and not expect to return home to their loved ones.
"Our focus right now is to support the family and our team in whatever way we can.
"We've also made as much information and footage as we have available to the police and will continue to cooperate with their investigation."