He was able to tell police the direction the shot was fired from. They visited a nearby property and arrested an 18-year-old.
Acting Detective Sergeant Andrew Mortimore said the youth would be charged in relation to the two shootings.
Mr Koroheke said that after being hit, "I reached up my back, pulled my hand out and it was covered in blood".
His girlfriend "freaked out" and checked the wound, where a large welt was forming, and told him: "You've been shot."
Mr Koroheke, a rigger and site foreman for a steel construction company, said he went into shock.
"It hurt like hell. The pain was ... I couldn't believe it. I was too scared to look around," he said.
The couple raced to Waikato Hospital's emergency department, where the injury was confirmed as being caused by a slug-gun pellet.
"I walked up and said, 'I think I've been shot'," Mr Koroheke said.
He passed out as doctors took x-rays and scans before dressing the wound and discharging him at 11pm.
Mr Koroheke said the incident was random and he was angry at whoever was responsible for almost ruining his holiday.
"I'm pretty sure they would have seen the pain it caused me because it almost dropped me straight away and that might have freaked them out a bit."
Mr Koroheke said he was glad he was standing in front of his girlfriend otherwise she would have been hit.
Hamilton police have condemned the actions of the "reckless" sniper as extremely dangerous behaviour.
Senior Sergeant Pete van de Wetering said Mr Koroheke was not the only person targeted on Christmas Eve.. A few minutes earlier and only a block away on River Rd in Claudelands, a 29-year-old woman was shot at as she was getting into her car outside a relative's house.
Megan Pace said she heard a "pop" from behind.
"I saw something fly right past the left side of my head towards the house. I don't know why but I moved when I heard the pop. If I hadn't have dodged it, it would have hit."
The mother of four called the shooter "stupid and irresponsible".
Mr van de Wetering said even though the weapon in that incident was a paintball gun, it too had the potential to do serious harm.
"You could be blinded."
Initially, police suspected that the Christmas Eve incidents were linked because they happened in the same area minutes apart.
But following last night's arrest, Mr Mortimore said they were investigating whether the Pizza Hut incidents were separate from the River Rd one.
Mr van de Wetering said such incidents could be "very dangerous, as everyone knows the capable force of modern air rifles".
"The danger of those things can't be underestimated."
In September 2008, Sergeant Don Wilkinson was killed with a .22-calibre air rifle in South Auckland while on an undercover operation.
