Even the most aggressive believers in automation, such as Amazon, still depend on human "pickers".
"We've been putting off working with an apparel company because it's so difficult," said Issei Takino, co-founder and chief executive of Mujin. "But Fast Retailing's strength is its ability to overhaul its entire supply chain to make it fit for automation. If we're going to take on this challenge, we had to do it with Fast Retailing."
Founded in 2011, Mujin develops robot motion and vision systems, such as 3D cameras. After human operators set up a machine with Mujin controllers, it can see and move without having to be repeatedly programmed.
For Fast Retailing, which sells 1.3 billion items of clothing a year, the need for automation is urgent, given a shortage of workers and rising storage costs.
"It's becoming extremely difficult to hire workers, and it's a lot more than people think," said Takuya Jimbo, a Fast Retailing executive in charge of changing the supply chain. "We have to be the frontrunner and continue trial and error because only the companies that can update their business models can survive."
The jointly developed robot, which was made by Yaskawa Electric, is already operating in Fast Retailing's main warehouse in Tokyo, but Mr Takino admitted that it was not able to handle all the facility's products, and that it needed further development.
For instance, the plastic packaging of the thermal underwear in Uniqlo's Heattech line is relatively simple for the robots to pick up, but this could become more difficult as Fast Retailing aims to switch to more eco-friendly paper bags.
The robots are able to pick up belts but these typically become unbundled as they are dropped into boxes. One solution would be for Fast Retailing to ensure that belts are sold in bundled forms.
On fears that robots will steal human jobs, Mr Takino said: "In the case of warehouses, there are no humans to steal the jobs from because the workers just aren't there."