Boris Johnson has "passed the ball over" to Tokyo as the city prepares to emulate London's success as a major sporting host.
In a formal ceremony, London's mayor signed a deal with his counterpart in the Japanese capital to work together ahead of Japan's stint as a host nation for the 2020 Olympics and the Rugby World Cup a year earlier.
Mr Johnson, who is in Japan on a three-day trade mission, wants London to benefit from the £10 billion of contracts the nation's year in the sporting spotlight will create and insisted there were "huge opportunities" for British businesses in the organisation of the games.
The Conservative MP said he was "figuratively and literally" passing the ball on to Tokyo as he handed over a 2015 Rugby World Cup ball as a gift.
He told the Tokyo Metropolitan Assembly: "We have so much in common. Not just our island status and the monarchy and an interest in tea, but a shared interest in using these great sporting events as a catalyst to deliver a better quality of life for our citizens.
"So, let us bind tightly as they do in the scrum and go forward together."
Mr Johnson warned Tokyo governor Yoichi Masuzoe that there will be a "mood of gloom and negativity" in the run-up to the Olympics that will disappear as soon as they are under way and then it will "be like the sun has come out".
The memorandum of understanding between London and Tokyo will see the two cities also work together on transport, tourism and the environment.
Mr Masuzoe said: "We would like to learn from the experiences of the city of London which had great success in hosting the Olympic Games."
Mr Johnson also announced details of a new partnership between London and Japan to target illnesses like Parkinson's and motor neurone disease.
University College London and Japan's largest pharmaceutical firm, Takeda, will collaborate on work to find more effective treatments for the neurodegenerative diseases.
The mayor said: "London is a world-leading scientific city with some of the greatest universities in the world, at the very forefront of the drive to understand terrible, life-altering diseases and how they can be stopped.
"Working with global partners is a crucial part of turning research breakthroughs into better treatments, and I'm absolutely delighted that Takeda is deepening its commitment to London through this partnership."