QBIT Robotics' repurposed industrial robot serves drinks from the corner of a Japanese izakaya pub operated by restaurant chain Yoronotaki.
Customers see a smiling tablet computer face and hear the robot discuss the weather and other topics while it prepares drinks.
It can pour a beer in 40 seconds and mix a cocktail in a minute.
It also uses four cameras to monitor its customers' expressions using artificial intelligence software.
Yoshio Momiya, Yoronotaki's Tokyo Area Manager, said: "There is a labor shortage problem in the restaurant sector.
"We installed this to solve this issue.
In addition to that, we are hoping to create a system where humans and robots can work together," he said.