"No one expected us to do what we achieved there," Sa'u said. "It was a great experience, one of the best of my career. Japan, the country, wasn't really behind us at the start so we went there to prove ourselves. Eddie drilled into us through the weeks beforehand that we could be the best Japanese team ever at a World Cup. We were positive and came away with the results and that made it even better."
Asked what his World Cup highlight was, Sa'u is unequivocal. The 34-32 win over South Africa. "The way we won proved we were a team that never gives up and always fights to the end. That was the best ever."
Prompted on how Jones, now England's head coach, prepared a team which looked one of the best drilled at the tournament, Sa'u laughs. "We had 100-and-something days before the World Cup in which we were together. That helped. We went through the basics time after time. We complained at the time but, in the end, that preparation was key.
"He's a hard man, he's little, but he gets his point across straight. Technically, he knows the game really well. He tried to keep the style of Japanese rugby but just tweak some little things and that's how good a coach he is - to be able to back that style and come away with the wins."
Referring to the victory over the Boks, which brought the tournament to life, Sa'u said:
"We knew if it happened it would be big. But it didn't hit us until later on that day or the next day. When we woke up, every newspaper and everything on TV was all about that game. [The next day] we walked around and everyone knew us. We felt like superstars."
Having played for Yamaha Jubilo for eight years, Sa'u decided the time was right to return to New Zealand with his family. He played for the Melbourne Rebels for a season in 2014 but, reading between the lines, didn't have a great time of it playing on the wing.
He feels better suited to centre and his distribution skills make him a good conduit between the hard-charging George Moala and Rene Ranger, with speedsters Tevita Li or Melani Nanai on the other wing.
"I went over to Japan when I was young - the opposite way to what many do now. I didn't understand much of [the culture]. But as the years passed, I understood more of it and the kind of people they are. That's why I was there for a long while. We loved it, but I always wanted to come back and give it a crack in Super Rugby so I'm just happy to get the opportunity."
The 28-year-old said the key to improving the Blues' ability to score points when putting teams under pressure - something they struggled to do in the narrow defeat to the Hurricanes - was communication and confidence. "We need to back ourselves and have the courage to play. We went through the review and saw we left a few points on the field. The boys know the structure works.
"They're going to come out firing," he said of the Reds. "They haven't won a game so they'll be looking for their first win.
"We've got a different challenge. We haven't won away in two years so we're going out there with the same mentality."
