The incident started at Nozawa's restaurant on the German island of Sylt, Suddeutsche Zeitung reported.
Two customers complained that their meals were unsatisfactory and left the restaurant without paying.
Nozawa ran into the customers at a bar. A fight ensued and the customers beat Nozawa.
The chef was brought to a hospital where he later died from injuries sustained during the beating.
The suspects are still at large, the newspaper said.