Explanation:

 Tokyo is hosting the second U20 Mayors Summit. 

Urban 20 (U20) is an initiative developed in 2017 at the One Planet Summit in Paris under the leadership of the Mayor of Buenos Aires and Mayor of Paris, and convened by the C40 Cities Climate Leadership Group (C40) in collaboration with United Cities and Local Governments (UCLG).

• Aims to tackle global challenges by leveraging the potential of cities as hubs of diversity and innovation.
• Urban 20 is composed of 25 global cities: Beijing, Berlin, City of Buenos Aires, Chicago, Durban, Hamburg, Jakarta, Johannesburg, London, Los Angeles, Madrid, Melbourne, Mexico City, Milan, Montreal, Moscow, New York, Paris, Rio de Janeiro, Rome, Sao Paulo, Seoul, Sydney, Tokyo, and Tshwane.