"It's my sister's birthday and I wanted to win for her. She's up in Auckland for a New Zealand water polo trial."
He had not expected to win, he said.
"I thought I might come second or third, but I didn't think I would come first."
He said he liked running for fun, but had never ran competitively.
Kiara Paul, 8, from Ngongotaha Primary School said she had been training for the event.
"I'm not nervous. I've been running laps around school at lunch time, and I did the cross country. It'll be easier than the cross country."
Sport Bay of Plenty School Sport team leader Gareth Yates said the event boosted children's confidence.
"This gives them an idea of just how far a full marathon is, and a true sense of accomplishment when they complete it - 42km over two months is a wonderful accomplishment for children."
https://youtu.be/upf9tKjFRHc