Nearly half of those infections were in Tokyo, where the city's metropolitan government said people in their 20s and 30s were driving the spike in infections.
Saturday's figures followed 249 news cases on Friday and 194 on Thursday.
Japan now reported 22,234 confirmed cases, including 990 recorded deaths.
Government minister Yasutoshi Nishimura said on Sunday that the resumption of a state of emergency was not necessary, describing the new cases as “light or asymptomatic” and not a burden to Japan’s healthcare system.