Japan scrumhalf Fumiaki Tanaka has warned that banking on Japan’s World Cup success will be a mistake.

In a year-end interview, the 30-year-old Tanaka, who plays in the Top League for Panasonic Wild Knights and in Super Rugby for the Highlanders, said Japanese rugby is still in crisis even after the national team won three of their four games at the Rugby World Cup in England.

“We need to make more of an effort to make this part of our culture, not just let it be a boom,” Tanaka said. “I still feel a sense of crisis. As we move toward (hosting) the 2019 World Cup, the Japan Rugby Football Union, the companies, the players all have to work together to raise the game.”

Indeed, after the first round of Top League games were reported to be sellouts — only to see large numbers of empty seats at the venues — Tanaka on Nov. 21 blasted the JRFU for lacking a sense of urgency in pushing the game.

It was a message few wanted to hear after this summer’s resounding success that started with Tanaka’s man-of-the-match performance in the Rugby World Cup’s greatest upset: Japan’s opening 34-32 win over South Africa.

“Frankly, I had thought the probability of our winning was low,” he said. “But we competed and immediately found we could be effective. We all became confident in that 80-minute span.

“I’m happy we could achieve such good results. So many people have thanked us. We owed a debt of gratitude, and though we were not able to achieve 100 percent, I believe we have repaid it.”

Following 2015’s huge success, 2016 will see Japan’s first entry into Super Rugby. On Feb. 27, the Sunwolves will play their first competitive match against the Lions in Tokyo. Like a number of his Brave Blossoms teammates, Tanaka will not play for the local side and was diplomatic about his rationale.

“Until now, I’ve played for the Highlanders and I’ve enjoyed it,” Tanaka said. “On top of that, if I were to play for the Sunwolves, it would mean one fewer Japanese player would be able to play (in Super Rugby). That was something I considered.

“Up until now I’ve been thinking about how to elevate Japanese rugby. To do this as an individual in 2016, I want to give my best in Super Rugby.”