The Governor of Osaka Prefecture today declared a medical state of emergency in the area as a surge of Covid-19 cases have put a strain on the local health care system.
Hirofumi Yoshimura said he was alarmed by the fast-spreading new variants.
"It has been said that the British variant is more contagious, and most of the cases we found in Osaka and Hyogo is the British one," Yoshimura told reporters in Osaka.
Osaka logged a record 878 new infection cases today.
Special coronavirus measures started earlier this week in Osaka and its neighbouring prefectures as Japan tries to minimise the impact to specific areas where infections are rising ahead of the Tokyo Olympics.
Under the measures, effective for one month until May 5, restaurants and bars in Osaka, Nishinomiya, Amagasaki, Ashiya, Kobe and Sendai are asked to close by 8pm (local time).
Residents are requested to stick to basic safety measures including mask-wearing, social distancing and avoiding non-essential outings.
Yoshimura has proposed cancelling a torch relay scheduled to pass Osaka City on April 14.