Satoyama's lawyer Andrew Speed described it as a "tragic accident"
Mr Tsuchiya had been in the country for only two weeks, and the crash occurred while the pair were returning to Auckland after spending the weekend in Northland.
Judge Thomas Everitt said Satoyama had an international drivers licence and had come to New Zealand to study and improve her English skills.
It was a wet morning and Satoyama lost control of the vehicle. The car she was driving slid down the hill and collided with an oncoming 4x4.
Satoyama had no memory of the accident, Judge Everitt said
She had driven from Auckland to see the Cape Reinga lighthouse with Mr Tsuchiya on the Saturday, and they slept in the car that night, he said.
They then headed back to Auckland on the Sunday morning, leaving at 4am, stopping for naps as they drove back down.
Judge Everitt said while Satoyama had no history of bad driving or excessive speed, she had a lack of driving skills and the crash was caused by a "high degree of carelessness".
There was no criminal intent to the crash he said. "She has pleaded guilty and is remorseful."
Mr Speed applied for a discharge without conviction, and said if convicted Satoyama would struggle to find a employment back in Japan due to the competitive job market.
Judge Everitt declined his plea, and described the consequences of a conviction as "vague".
"I am not convinced that the consequences of a conviction would outweigh the gravity of the offence."
"The fact that a life was lost is a fact that can't be ignored," Judge Everitt said.
"You have caused the death of another human being and that will weigh heavily on your conscience for quite some time."
Judge Everitt sentenced Satoyama to a six-month ban from driving, and ordered her to undergo a compulsory driving improvement course.
