Kobe had made him and offer but so too were Racing keen for him to extend his stay. "It was a tough choice," says Carter. "I have loved my time in Paris and really enjoyed being with the club and living in France.
"But with the World Cup going to Japan in 2019 and the Olympics there in 2020, it is a really exciting time for rugby there. The opportunity to help grow the game there and promote rugby in Japan was really appealing.
"I have spent a bit of time there already, worked with kids there to try to get them interested and I have really enjoyed it.
"But the other big thing is Japan is that much closer to New Zealand and with the way season is set up, my family will be able to spend more time in New Zealand. They have sacrificed a lot for me so this felt like the right thing to do for them."
Japanese clubs have enjoyed considerable success on the recruitment front in the last five years or so with the likes of Jerome Kaino, Ma'a Nonu and Sonny Bill Williams all having spent time there.
But unquestionably, even at 35, Carter is the biggest signing in Japanese club rugby history and his popularity, profile and marketability will do a significant amount to raise the profile of rugby ahead of the World Cup.
Carter says he hopes to return to action in the next few weeks and his goal is to make a strong contribution to Racing's title challenge. They currently sit within the playoff zone but there is a long way still to go.
He would love to sign off with another winner's medal having helped Racing to the Top 14 title in 2016 when they beat Toulon in the final, which was played in Barcelona.
Racing also went on to play in the final of the European Champions Cup that year, but were defeated by Saracens in the final, denying Carter the chance to join a rare group of players who have won a Super Rugby, World Cup and European Champions Cup title.
He will head to Kobe once his commitments with Racing finish next year.
