At 4:40 a.m., the perpetrator produced a knife while demanding cash from a male cashier, 29, at an outlet of Sunkus located in the Ebisu area. The cashier then placed about 480,000 yen in cash in a bag for the man before he fled the scene.
The cashier was not injured in the incident.
Standing up to 180 centimeters in height, the man was wearing a breathing mask and a jacket with a black hood. His estimated age is not known.
Prior to committing the crime, the suspect pretended to be a customer purchasing a canned drink.
Police are analyzing security camera footage in an attempt to identify the perpetrator. His whereabouts are sought after on suspicion of robbery.