In the book History of Japan by Richard Mason, the author states in chapter 3:
In the year 645, opponents of the Soga leaders struck back. The final coup was preceded by careful preparations that included a famous meeting at a football game between the two leading Soga aristocrats, the head of the Nakatomi clam, named Kamatari (614-69), and a young imperial prince, Naka no ōe (626-71).
To what football is the author referring? It obviously can not be association football (soccer) or American football, as these were not introduced to Japan (or even invented) for more than a thousand years after the events described above.