The shotgun concealed in his trousers, he entered the store and pulled down his hat to hide his face while store owner John Zhao was serving customers.
However when Mr Zhao saw he was jostling in his bag in preparation to commit a robbery he immediately confronted him with a wooden baton.
Wihapi tried to reach for his shotgun, which was still hidden in his trousers, but was chased from the property before he had could grab hold of it.
It was at this point that the unassuming hero, a pink fairy, joined in the chase.
Napier landscaper Liam Fontaine was at the diary getting ice cream for his nieces when he saw a "suspicious looking" man, whose face was covered, walk into the store.
Donned in a pink fairy costume, he had just completed a Breast Cancer fun walk with his sister and her daughters.
"I had put my pie and my drink into the car when the store owner chased this man out of the shop," he said.
The 23-year-old took off after the robber, along with another customer, a 14-year-old male.
"We both got him on to the ground and pinned him there while my sister was in the dairy helping out and calling the police."
The man put up a bit of a fight, he said, but the pair put him in his place.
"We just told him 'look, don't make more trouble for yourself. The more you fight the worse it's going to be'."
He said police took over when they were able to flag down an off-duty officer.
When spoken to by police, Wihapi admitted what happened and said he just wanted to go back to prison.
Senior Sergeant Kevin Stewart went on to pay special thanks to the "fairy hero" for saving the day.
"We want to give our pink fairy hero and his acquaintance a big pat on the back for preventing this offender from getting away."
The landscaper said he had not expected his actions to receive so much attention and hoped some attention would go to the teenager who also helped catch the robber.
"It's been pretty full on, I was quite shocked about how much it went viral."
Special mention of "the pink fairy" was made in court yesterday, prompting smiles and chuckles from those in the room.
Mr Zhao and Mr Fontaine were both pleased to hear of Wihapi's guilty plea.
"I see too many dairies being burgled," Mr Zhao said.
"I would be quite interested to see what he gets for that," Mr Fontaine said.
Wihapi was remanded in custody and will appear for sentencing on December 19.
The maximum penalty for attempted aggravated robbery is seven years' imprisonment.
