The first Tokyo Marathon was held on 18 February 2007. However, years prior to 2007, Tokyo Marathon actually consisted of two marathons - the Tokyo International Marathon which took place on even years, and Tokyo - New York Friendship International Marathon which took place on odd years. In the inaugural year, 1981, both marathons took place. However, because it was not possible to support two marathons a month apart in the same city, from 1982, the alternating format went into effect.