The brother and sister, from Surfers Paradise, won the top boys' and girls' prizes in the rescheduled tournament at the Brendale course on Friday.
Manato, 17, shot a two-under par 68, on a day of heavy showers and blustery wind, to land the boys’ title at the second attempt.
Sister Haruhi, 15, birdied the first play-off hole to beat Tuuki Takada, from Southport, after both had rounds of 71.
It was Haruhi’s second overall victory in the CSJC having won in 2019 and finished runner-up in 2020.
Among their prizes were pin flags from the 2021 US Masters, signed sent by Cameron Smith, with signed caps for the A Grade runners-up.
“We had to go out in the rain (for the play-off), but it was worth it. If it was a countback I would have lost,” Haruhi said.
“I found it tough out there. I missed quite a lot of fairways, but my short game was pretty good today.”
Manato described conditions as “pretty hard and pretty wet” but it was a “great way to start the year. I think Mum and Dad are very happy!
“The wind and rain made it difficult. My gloves and clothes were wet and you had to concentrate more than usual on hitting the ball clean.
“But I really enjoyed it. I thought the course was really good today.”
Taj Egea, from Brookwater, pipped Wantima’s Jayke Merrell to second spot on countback after both had rounds of 71.
Like Manato, Egea praised the course saying it looked “amazing”, while Merrell thanked the officials and volunteers who made the CSJC possible.
Organisers Ken McKay and Shane Johnsson paid tribute to the greenkeepers for the quality of the course and Wantima Country Club for its continued support of the CSJC.
The 2021 tournament was rescheduled after torrential rain forced a late postponement on December 10 and was held with additional COVID-19 precautions in place.
At the same time Cameron Smith, who grew up in Bray Park and learned to play at Wantima, made a stunning start to the first US PGA Tour event of 2022.
He was 7600kms away in Hawaii by had a first round 65 to lead the Sentry Tournament of Champions - and was never caught, carding a four-round total 34 under par to eventually beat world number one Jon Rahm by a shot.
However, Smith still found time to send a video message to Wantima saying: “Thanks to (Classic organisers) Ken McKay and Shane Johnsson for their help throughout the year.
“Thanks to all the sponsors, it means such a lot to the event and to support Wantima Country Club. It feels like only yesterday I was there with some cut-down clubs, following Dad around.
“Thank you all for competing. Congrats to the guys and girls who won and hopefully I will see you guys in December.”
A Grade Boys
Gross winner: Manato Nakatani (Surfers Paradise) 68/69
Runner-up: Taj Egea (Brookwater) on countback 71/72
Nett winner: Jayke Merrell (Wantima) 71/69
A Grade Girls
Gross winner: Haryuhi Nakatani (Surfers Paradise) in play-off 71
Runner-up: Tuuki Takada (Southport) 71
Nett winner: Summer Sadler (Emerald Lakes) 72/72
B Grade Boys
Gross winner: Jack Jones (Keparra) on countback 75/70
Runner-up: Justin Hammett 75/69
Nett winner: Kiedyn Heddie (Parkwood International) 78/70
B Grade Girls
Gross winner: Tiyara Samararatne (Mt Warren Park) 82/74
Runner-up: Saskia Knevitt 85/73
Nett winner: Alicia Ludi (Hope Island) /Alyanna Antonio (Virginia) 74
C Grade Boys
Gross winner: Eli Cookman (Tewantin-Noosa) 86/72
Runner-up: Robert Nieuwoudt (Gainsborough) 87/70
Nett winner: Kane Johnsson (Wantima) 103/68
Nearest the pin
Boys winner: Max Russell (Royal Pines)
Girls: winner: Mikayla Dyal (Keperra)
Boys Champion - Tyler Duncan
Girls Champion - Lion Higo
Boys Champion - Mitchell Hennessy
Girls Champion - Chloe Nam
Boys Champion - Andrew Park
Girls Champion - Haruhi Nakatani
Boys Champion - Harry Takis
Girls Champion - Justice Bosio