There were three deaths on Saturday and three more on Monday, according to the Tokyo Medical Examiner's Office.

According to the report of Xinhua news agency, Tokyo saw the highest temperature of the year over the weekend.

The Japan Meteorological Agency (JMA) reported that the temperature in the Japanese capital rose to 34.2 degrees Celsius and reached 36 degrees Celsius over the course of two days.

The recent heatwave has led to a significant increase in heatstroke cases across Japan. Some 9,105 people were rushed to emergency rooms across the country due to heatstroke last week, according to the Fire and Disaster Management Agency under the Ministry of Internal Affairs and Communications.

The data shows that this represents a substantial increase of about 6,800 cases compared to the previous week, which saw 2,276 cases.

The number of heatstroke patients this year almost doubled compared to the same period last year, with 4,026 cases recorded. In the latest cases, 19 people have died and the condition of 210 is critical.

Officials advised the public to take preventive measures for heatstroke and to stay hydrated and use air conditioning appropriately to combat extreme heat.