Keiji & Okada

[Sonyme]

I suppose this ought to be on Sport, but that site keeps returning server error when I tried posting. It is a question from a quiz anyway so here goes.
At which sport have keiji & Okada been world champions? - I think it is one of the martial arts but can't find anything specific.

[glasman]

Wrestling, i think??

[Sonyme]

Thanks for the suggestion - will try to find out more.
Can't find Okada anywhere in any sporting field, but a Keiji is listed in Judoka, but without any First names or initials it's hard to say whether he is the one the quiz master is referrin to