The Fijian second row forward has matured like a fine wine since switching to Saints from French second division club Agen in September 2016.
And the Northampton coaches clearly think there is much more to come from the player as he penned a new two-year deal at Franklin's Gardens on Wednesday.
But Ratuniyarawa certainly won't be sitting back and relaxing after earning a fresh contract.
Instead, he constantly states his desire to improve.
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And that determination has been in evidence on the field in recent weeks, with the 6ft 6in star starting to cement himself in Saints' second row.
"I've developed a lot as a player, but I still have a lot to learn," said the softly-spoken player.
"I came here with an open mind, wanting to learn new things and I think it's helping my game.
"I'm happy I've been given many opportunities to play and I'm just giving my best to be better every week."
So what does Ratuniyarawa, who possesses an eye-catching offloading game and immense power, feel he needs to improve?
"For me, it's about improving my defensive work and working off the ball," he said.
"It's about looking where the ball is and trying to make a good hit to help the boys out in defence and to work together as a unit, sticking to our systems led by the coaches."
Ratuniyarawa has settled in superbly at Saints, especially considering he has only been able to have one pre-season with the club.
And it is clear what he likes most about life in Northampton.
"It's playing here at Franklin's Gardens, playing in front of a very loud crowd," said the Sigatoka-born star.
"My family really likes it here, they're really settled in and that really helps me to play well.
"If the family is happy, then I'm happy too.
"I'm happy to be playing well and really looking forward to another two years here."
Ratuniyarawa is part of a Polynesian crew at Saints.
"It's good to have a few Island boys here at the club - it really helps me a lot to settle here," he said.
"They have been here for quite a while, especially Ken Pisi.
"We've also got Campo (Campese Ma'afu), Ace (Ahsee Tuala) and Nafi (Tuitavake) and it's good to have them here because we're a long way from home.
"It helps in working together in training and knowing the game plan."
“After the game we always sit together, have food together and have a chat.
“We look back on the game and have a social life away from rugby.”
Ratuniyarawa and Co have a big job to do on the field this Friday as they host Harlequins in the Anglo-Welsh Cup.
If Saints can get the win they want, they will book a semi-final spot.
And that is a real target for the remainder of this season, as well as lifting the club from its current standing of 10th in the Aviva Premiership.
“We’re working on finishing the season on a high as a team,” Ratuniyarawa said.
“We want to win some silverware for the club and finish the season well.
“It would give us a better platform to start next season.”