Defence counsel Rupert Ward said Hayashi had told him that in Japan there was no prohibition against crossing the centre line.
He had been driving here on an international licence, and in his homeland had no driving offences, and in fact was the owner of a "golden licence".
Hayashi was remorseful and now understands that he could have caused an accident, Mr Ward told the court.
Judge Tony Couch noted that they also drive on the left side of the road in Japan.
He fined Hayashi $500 plus $130 in court costs, and also disqualified him from driving in New Zealand for a period of six months.
However, the judge admitted he was unsure what effect it would have in Japan, "possibly none", he said.
He ordered Hayashi to pay the fine today before he jets out of the country tomorrow.
The case comes after a spate of fatal crashes involving tourist driving, including a horrific smash last Thursday that claimed the lives of three Hong Kong nationals outside Wanaka.
Driver Wing Fai Chan, 60, also known as Allan, and two female rear-seat passengers - Kwai Tei Chong, 61, also known as Connie, and Yin Wan Ng, 56 - died after their hired vehicle collided with a truck and trailer unit on State Highway 6 near Luggate, in the Wanaka area, about 4pm.
While tourists are blamed for fewer than 2 per cent of annual fatal crashes, the rate soars to 25 per cent in the tourist hot-spots of Queenstown and Wanaka.
Overseas drivers were involved in 493 injury or death crashes in the Otago and Southland regions from 2009 to 2013.
The New Zealand Transport Agency is working with the Ministry of Transport, police, local councils, the Automobile Association and the tourism sector to target tourist hotbeds.
They are making sure rest areas and scenic spots popular for photographs are safe to negotiate and include clear road signage.