What kind of football was played in 645 Japan?

Question

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.

Answer 1

It's referring to kemari, a variation of an ancient Chinese game of kicking a ball-like object around. Originally a military training exercise, it evolved into a sport played by teams of 12 - basically, proto-football - during the Han and Tang dynasties, before spreading to Japan around AD 600 along with the spread of Buddhism.

Note that the original source, from Nihon Shoki, actually records the meeting as:

偶預中大兄於法興寺槻樹之下打毬之侶、而候皮鞋隨毬脱落、取置掌中、前跪恭奉。中大兄、對跪敬執。自茲、相善、倶述所懷。

Technically, 打毬 could have been dakyu, a polo-like game that also originated from China. However, the earliest other reference to this game dates to the 8th century, decades after Nihon Shoki was compiled in 681. It also makes little sense that the future emperor would lose his shoes playing proto-polo.

So most subsequent Japanese sources have assumed that the original record referred to kemari instead. For example, this pre-war painting depicting the meeting:

^{Source: Ise Jingu Museum, National History Illustrations}