Yuki Tsunoda used to be known for his four-letter outbursts on the team radio -- this season it's for his controlled mastery of four wheels.

Where the likeable Japanese star would once rant and rave at perceived injustices out on track, nowadays he is calmness personified. Almost.

This new self control is paying off handsomely with his points tally for 2024 already at 19, two more than the whole of 2023, with 15 races still to go.

Chatting cheerily under a large umbrella at his RB team garage ahead of this weekend's Spanish Grand Prix Tsunoda's sunny outlook lit up the damp day.

"I'm happy with my progress. Sometimes I do have to think before pressing the radio button in the car, like when there's traffic.

"I have to force myself to calm down, but the emotional control is coming more naturally, or I'm just in silence," the 24-year-old commented.

"For sure I'm on the right path. But you can't just shut up all the time, you still need feedback!"

He says his teammate Daniel Ricciardo has played a key role in his personal development which has been rewarded by his Red Bull employers handing him a contract extension with the team, formerly racing as AlphaTauri, until at least the end of 2025.

"Daniel is the more complete driver, with emotional control, he's very strong on that," said Tsunoda.

"I started in a pretty bad positon. I started to learn why he's doing much better than me, he's helped me become more consistent throughout the year.

"With Daniel it's working really well, we have a relationship on and off track."

- 'Crazy trajectory' -
Tsunoda's boss, RB team principal Laurent Mekies, is excited about the giant strides the Italian-based Japanese driver has taken on his F1 journey.

"What Yuki has done now in his fourth year - you expect these steps to come early in the career, but on his fourth year, to make such a huge leap is credit to him," Mekies told F1.com recently.

Mekies believes the sky is the limit for the Japanese star.

"I have been fortunate in my life to witness that in so many champions," said Mekies. "They progress and they get faster, and faster again.

"If you were asking us what is stopping us from sleeping right now, it would be the responsibility we feel in trying to make sure Yuki has the right environment to do more steps.

"Because who are we to know that it's the last one? We don't think it's the last one. We think there may be a lot more to come, and that would put him on a crazy trajectory."

Another factor in Tsunoda's emerging maturity was his decision to base himself near the RB factory in Faenza in Italy.

"I've lived in Italy for two and a half years now, the town itself is more like home, rather than a place where I'm living to be near the team.

"Most of the team members live close by, we have have good conversation, a good relationship. So this kind of stuff is definitely positive."

Tsunoda has five top 10 finishes this term - and has scored points in five of the past six races.

Like his home country's famous cherry trees in spring, he is blossoming.