We were about to say treat this as 95% certain as we haven't been able to confirm it but then we looked at the email again and David Monti has sent an email confirming it
A source wrote:
Quick note from Tokyo:
Geoffrey Mutai will not start because of injury. According to his manager Gerard van de Veen, this was already decided some weeks ago, but the organizers have not announced his withdrawal from Sundays race.
Mutai himself sent out a tweet last week about running the Prague Half on March 28.
David Monti wrote:
Geoffrey Mutai. Is out of the Tokyo Marathon. I am not sure why this was not announced earlier...