"They said that 'if you're not on a New Zealand passport and you've been here for four years, you can play for the team'. But I've been here for four years and they said I can't play for the New Zealand A team. It's not fair."
The teenager grew up in Tonga, but has been in New Zealand since late 2010, attending school and playing rugby.
Although he would take the chance to play for New Zealand in a second, he said, he was starting to look at options across the Tasman, where he had had offers.
He has also had offers from Europe and from local clubs, but has yet to be contacted by the New Zealand Rugby Union to talk about his eligibility. "Maybe I'm not good enough to stay here," he joked.
"But that's one of my goals this year - to play for the New Zealand A team. If I can play with them, then maybe I'll change my mind from going to Australia.
"If I have the chance to play for the All Blacks, I'll take it. If I can't make the All Blacks and I can't make the Wallabies, then maybe I'll play for the other one - [Tongan national rugby team] Ikale Tahi."
At the College Rifles ground in Remuera yesterday, Tupou was one of dozens of upcoming players picked for the Blues and Chiefs Under-18 squads.
Barely 20 seconds into the second match of the day, he scored with his first touch of the ball.
One parent was heard telling another: "There's that Sacred Heart kid. He is something else."
Taniela Tupou is tackled playing for the Blues Under-18s against Chiefs Under-18s yesterday. Photo / Richard Robinson
Later, Tupou stopped to shake hands with people who called out to him and laughed with players from both sides.
He said being recognised on the street was something he was still getting used to.
"I went to Manukau and people were coming up to me asking me to sign pieces of paper. Sometimes now, I just wear my hoodie and cover my head."
Tupou goes to Tonga today for a week-long holiday and is looking forward to seeing his family, especially mum Loisi.
His face lit up when talking about home and when asked if his village, Vaini, is near the Tongan capital, Nuku'alofa, he roared with laughter: "Nah! It's back of the bush, man. It's far as from town. We come from a poor family. My dad passed away in 2005 and that's why I'm trying my best in rugby ... my family are my motivation."
Being able to provide for his family was the ultimate dream - and making his mother happy.
"She tells me to keep doing what I'm doing, keep it humble and stay the same. Talk to people and don't be snobby. Don't think you're a star. Be the same Taniela."
Watch new footage of the young rugby star in action here.