Tonight the 21-year-old (who celebrates a Christmas birthday) will be on the Brisbane Broncos wing up in Townsville for the sunshine state derby against the North Queensland Cowboys.
Little wonder the Hornby club product is still pinching himself at his whirlwind career shift.
"I haven't really come to grips with the fact that I'm playing NRL at the moment," Manihera admitted before travelling to the tropical north.
When the Broncos' call-up came, the New Zealand Maori representative had just celebrated a big moment in his career a try on debut for the Queensland Residents team in a State of Origin curtain-raiser at Suncorp Stadium on June 11.
"I was on my way to Dolphins training a couple of days later when I got a call to say Wayne (Bennett) wanted me to come to training at the Broncos."
Manihera's first thought was someone was pulling his leg. But the caller was fair dinkum. Broncos' under-20 team coach Anthony Griffin had been asked to track down his former Redcliffe charge at Bennett's behest.
Manihera did a snappy U-turn and made his way to the Broncos' Red Hill training base. "A couple of days later I was on the flight down to Canberra. It was all pretty surreal, it happened so fast."
He says he got "a bit of a fright" at how quickly things evolved. One day he was playing part-time, the next he was suiting up in the same Broncos backline as Origin stars Karmichael Hunt and Darius Boyd.
The Kiwi made his NRL debut in the Broncos' loss to the Raiders on June 15. Averaging more than 100m a match with the ball under his wing, he has kept his place since for games against the Wests Tigers, Penrith Panthers and the Bullodgs.
It's a far cry from his first footy steps as a five-year-old with Marist Western Suburbs. Footy is in the blood cousin Tane Manihera, a former Canterbury halfback, is still playing professionally for Whitehaven in England at 33.
Young Kaine spent several seasons with Papanui before linking with Hornby where he graduated to the Panthers' premier grade team at 16.
He made his Canterbury Bulls debut in 2004 and was at fullback when Phil Prescott's team suffered a last-gasp loss in the 2005 Bartercard Cup final against the Mount Albert Lions.
The teenage Manihera, who scored 13 tries in 17 Bulls games in grand final year, caught the Broncos eye and the club's then recruitment chief, Ivan Henjak, lured him to Queensland climes.
"It was a pretty easy decision to make because I had two brothers living over here," he said. "I thought footy wasn't going anywhere (in New Zealand) and I didn't know if it was going to get any better."
While Christchurch is still home his mum and dad Charlie and Ra Nikorima remain based here, Manihera feels "real settled in Brisbane" now.
He trained with the Broncos after his arrival but was farmed out to Redcliffe, one of the NRL giant's feeder clubs, and soon broke into the Dolphins' first team. Manihera's big break came this year when he made the City team for the Queensland Residents' squad trial and was selected for his run-on Residents debut against New South Wales.
As the two teams strolled out onto the Suncorp Stadium sward for a pre-match reconnoitre, Manihera found himself staring at a familiar face his former Canterbury Bulls team-mate Charlie Herekotukutuku, now a North Sydney Bears utility.
"We hadn't seen the NSW team names until the day of the game and it was a big surprise to see Charlie H there at hooker.
" But I was happy to know one of the (Bulls) boys was playing for the (NSW) Residents. I managed to catch up and have a chat with him before the game."
Herekotukutuku had the last laugh NSW won 24-16 but Manihera made an instant impact, scoring Queensland's first try in the second minute. As he crossed the white chalk, he took time to honour the memory of Cath Whitehead, a Christchurch woman who played an important part in his early upbringing.
Cath, wife of Canterbury and New Zealand rugby league life member Bill Whitehead, "passed away a couple of days before the game," Manihera said.
"They didn't want to tell me till after the game, but I found out and it was a bit of a shock, so I scored that try for her. She was like a second mum to me, through primary school and high school. She looked after me and was a pretty big influence on me.
"It (dedicating the try) was the only thing I could do at the time."
Growing up in Christchurch, Manihera always aspired to play in the NRL but admitted in recent years, "I didn't think it would happen. Now that it has, I just want more, and more ..."
He is not yet on a full-time contract but his goal is to "keep my place in the team" and secure a deal for next year.
The NRL has been everything he dreamed it would be. The pace is phenomenal. "Everything's so much faster than what I'm used to, it's more physical and everyone's more switched on.
"All the players and the coaches are up another level. Everyone brings so much more to the table."
He had a nervous start against Canberra, knocking on the ball with his first touch, an error which led to a Raiders try. But he grew in confidence as the game went on and made a 70m break, only to be hauled down 10m short of the line, after stripping the ball from a Raider's grasp.
The NRL rookie celebrated his first victory in his first home game against the Tigers, but has been on the losing end against Penrith and the Bulldogs.
It won't get any easier at Townsville tonight where the Cowboys are hard hombres to beat, even with superstar Johnathan Thurston on the disabled list.
Manihera now finds himself playing with and against some of the game's legends. Broncos, Queensland and Australia captain Darren Lockyer returned at stand-off half last weekend against a Bulldogs team led by Sonny Bill Williams at his inspirational best.
"Playing with (Lockyer) was pretty special, especially knowing that some of the biggest stars in the game would love to play with him. And Sonny Bill is someone I look up to as one of New Zealand's greatest players."
Being coached by Wayne Bennett is an education in itself, Manihera says. "He's one of the best coaches in the game and to be coached by him is something I'll never forget. He's given me a lot of help since I've been here.
"He'll be missed (when Bennett moves to St George-Illawarra next season). But Ivan Henjak will do a great job as his replacement."
Henjak is the man Manihera has to impress now and the Cantab, who cannot believe his change in footy fortune hopes he gets the rest of the season to strut his stuff.