"The reason I organised this group was to give back to the kids. I've been teaching tertiary and wanted to give back. Our kids are sponges. I'm giving them good teachings and learnings while they are young and while their hard drive still has a lot of space," he said.
"I give them that knowledge."
He said the classes - for school students "hungry" to learn te reo from John Paul College, Rotorua Girls' High School and Rotorua Intermediate - had been popular since launch.
"I put out a notice for people to attend the classes which filled up quickly.
"I teach in a fun, friendly, non-threatening and patient environment and cater to everyone's different learning styles.
"When a student incorrectly pronounces a particular sentence; I correct them without them noticing which I then pass onto the whole class which benefits everyone," he said.
"I'm on this canoe and I'm paddling along beside them."
Rotorua Intermediate student Alana Bennett joined Hiini's classes because she thought it would be important to learn te reo being an official language of New Zealand.
"I like the challenge of learning different words and sentences which is fun," Alana said.
Hiini's school student classes are held on Friday afternoons at Nuku Te Apiapi behind Te Arawa Lakes Trust on Haupapa St.
When it came to his adult classes, Hiini said he had noticed a recent increase in non-Māori learning the language.
"I was told te reo should only be taught to Māori but it should be taught it to anyone who's hungry to learn it especially when the language has been declining for a long time," he said.
"Knowing te reo gives you an appreciation of the culture.
He teaches four aspects of te reo including its pronunciation and flow, thinking from a Māori perspective and, most importantly, grammar.
"I get right to the nitty-gritty of a sentence by helping them understand why a sentence is structured because while native Māori speakers might be immaculate, when they're asked why they say certain Māori sentences in the way they do they're unsure," he said.
"That wider thinking is really important because it's when you start seeing the beauty of the language."
Peter Vial from Chartered Accountants Australia and New Zealand said he and his company had been learning te reo, tikanga, mihi and pepeha from Hiini over Zoom for two years and it had been "awesome".
"We are very much behind the Government's initiative to encourage te reo use and fluency," he said.
"It's really helped with improving our outreach to Māori business and accountants.
"It's very critical New Zealanders have an appreciation and understanding of te reo being an official language of our country."
Vial said the four aspects Hiini taught were what made the learning special.
"I'm Pākehā but I've learnt so much through thinking from a Māori perspective including learning my own heritage and from that want to know more about my ancestors so I can recite my own pepeha," he said.
