Tokyo Governor Yuriko Koike says she plans to draw up by December a strategy to effectively reduce the city's carbon dioxide emissions to zero by 2050.
Koike announced her plans at the Urban 20 Mayors Summit talks, which began in the Japanese capital on Tuesday.
Representatives from 26 major cities around the world are taking part in the event to discuss global warming, sustainable economic growth and other shared concerns.
The Paris Agreement on climate change aims for virtually zero emissions of global greenhouse gases by the latter half of this century.
Japan's government has set a goal of cutting domestic emissions by 80 percent by 2050.
The Tokyo Metropolitan government has gone a step further, and plans for effectively zero emissions in Tokyo by 2050.
The strategy will include a 40 percent reduction in incinerated plastic waste by 2030.
The U20 Mayors Summit wraps up on Wednesday with a joint statement, which will be formally presented to the Group of 20 summit in Osaka next month.