"We were so excited we screamed and we cried when we found out," Dennihe said.
"It was so good that we were here in the music room at school when we found out because we could celebrate with Mr Holt who has given us awesome support."
Whanganui High School music teacher Brett Holt has encouraged the duo and filmed their performance for their Smokefreerockquest entry which has been viewed over 1600 times on YouTube.
"We had to submit a video entry this year and we did 15 takes before we were satisfied," Dennihe said.
"Mr Holt was so good about letting us do that."
Although Dennihe is a Year 13 student and Toa is in Year 11, they had heard each other's voices at school events and have been singing and playing together for a while.
"I was so pleased when she asked me to sing with her because I love her voice and I was so pleased that she liked mine too."
Dennihe played piano and shared vocal harmonies with Toa when performing their original song for their entry.
"Dennihe wrote the song and I did the te reo translation," Toa said.
Both young winners are Māori and wore Ei (woven floral headdresses) with their school uniforms to honour their Pacific culture when performing their entry.
"We write songs that are relatable for teenagers and they are about us, our friends and our teenage experiences," Dennihe said.
While Toa said he is from a very musical whānau, Dennihe said she is the singer and musician in her family and said it has been her focus for as long as she can remember.
Smokefreerockquest band and Tangata Beats entries closed on Friday and the winners will be announced on August 7.
Regional winners will submit new footage for selection as finalists to play off at the Smokefreerockquest national final in Auckland on September 11 and 12.