They are not quite the Thompson Twins, but Luke and Anna Thompson brought sibling rivalry to a whole new level when lock Luke lined up for Japan in their opening World Cup match against France.
Tomorrow Anna will be named in the Silver Ferns squad to face England and Australia next month. Both have represented their respective nations for several years, but have only got to see each other play recently; Luke travelling to Singapore to support the Ferns in July, while Anna caught Japan's clash with Italy during a European holiday post world-championships.
While Anna is known nationwide in netball-mad New Zealand - and even has a cocktail named after her in Christchurch ("I've tried it," laughs Luke, "it's not a bad drop") - her older brother remains relatively anonymous in both Japan and New Zealand.
"I'm happy to concede that one to Anna," says Luke. "Japan is huge. They talk about a stadium of four million people here; well Tokyo railway station has that amount passing through it every day - and rugby doesn't touch the mainstream."
As well as Anna (25) and Luke (30), Sean (28) was an accomplished junior rugby player and is now an accomplished harness racing driver.
The brothers would often corral Anna into backyard touch rugby games, as well as use her for hours of passing practice.
"We were always encouraged to practice our skills," says Luke, "she was often the nearest person around and didn't get much of a say in the matter."
Now a Japanese citizen and unsure if he will ever return home, the tale of Luke's switch is a fascinating one.
He made all the Canterbury representative teams as a junior, and had played NPC rugby for the province but in 2004 saw his path blocked by the return of Brad Thorn and the presence of Chris Jack.
Through an association with Canterbury the 22-year-old went to play for Sanyo on a one-year deal and eight seasons later is firmly ensonced in the Land of the Rising Sun.
"From the start I loved it," says Thompson.
"It is a great lifestyle and a fascinating culture plus I was a fulltime professional."
Playing for Canterbury, he received about $1000 a year, barely enough to cover petrol, and was living off student loans. When the year in Japan was up there were no obvious options at home, so he stayed.
The rugby was fast, though not as physically or technically demanding as in New Zealand. He says it has improved markedly during his time, thanks to better coaching and a better quality of foreign players.
"Some used to come here for a holiday and to put their feet up," says Thompson. "That still happens but generally players are coming here younger and contracts are not as easy to come by."
While the Japanese have genetic physical limitations that will always be hard to overcome - it is hard to think of a Japanese forward plying his trade professionally offshore - they have made slow but steady progress in recent years.
They pushed Fiji all the way in the last World Cup before a 12-12 draw with Canada, while the unfortunately named Brave Blossoms beat Samoa and Tonga in the 2010 Pacific Nations Cup.
The domestic competition is still laden with foreigners, but authorities are doing what they can to limit their influence; in 2012 clubs will only be allowed to field two imports in the playing XV at any one time, down from three this year.
Yesterday's match was Thompson's 35th since his debut against Hong Kong in 2007. One of his proudest moments was the match against Fiji four years ago in front of 45,000 in Toulouse, though that will surely be superseded by the clash against the All Blacks on Friday in Hamilton.
"It's the ultimate as they are the best in the world," says Thompson. "They will be formidable but it is a great chance for us to show the world we have improved."
The Thompson clan will be out in force in the crowd.
His parents have taken time out from their job as harness racing trainers and are travelling round the country in a campervan, together with brother Sean and his wife.
Meanwhile, Anna hopes she will get to a match somewhere, Silver Ferns commitments notwithstanding.