Scrum V sends Newport Gwent Dragons head coach Kingsley Jones to catch up with Japan defence coach Leigh Jones.
The former Dragons coach was one of the men behind the huge effort that saw Japan spring the shock of this, or any other, World Cup - beating the mighty Springboks.
The Brave Blossoms had only won one World Cup match - against Zimbabwe - in their history before this tournament, but beat South Africa in their opening pool game 34-32 after opting to go for a late winning try.
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Watch all the analysis on Scrum V Rugby World Cup Special on Sundays, BBC Two Wales; available on iPlayer for seven days after transmission.