Donna Nelson found guilty of importing methamphetamine into Japan

Australian grandmother Donna Nelson has been sentenced to six years' jail by a Japanese court after being found guilty of importing two kilograms of methamphetamine into the country.

Nelson, 58, alleged a love scammer tricked her into carrying the bag with the drugs hidden, after she was caught at Tokyo's Narita Airport in January last year.

She picked up the travel bag during a three-day stop in Laos, claiming she had been tricked into believing it was a sample case an online love interest needed for his fashion business in Japan.

Nelson had sparked an online romance with a man, known as Kelly, with the pair interacting via messages and online video chat for two years.

Donna Nelson had planned to meet a man named Kelly in Japan.  (Supplied)

After several failed attempts to meet in person, Kelly bought a flight for Nelson to Japan, which included the Laos stop where an associate of Kelly's delivered the bag.

Nelson moved her belongings into the new travel case, telling the court she did not want to manage two bags for the final leg of the journey.

The court ruled Nelson ignored many red flags about the man she had met online, including the strangeness of the request to bring in a bag from Laos.

There was also the fact Kelly had an associate in Laos who could have easily taken the bag to Japan himself, and the bag was not of any remarkable quality.

The court found Donna Nelson should have acted on red flags that were raised when she was asked to take a bag from Laos to Japan. (Supplied: Yoshitaka Enomoto)

The court also ruled Ms Nelson had expressed opposition to collecting any bags just a month before her departure.

"The strangeness of the request was not resolved and the doubt something illegal could be inside the suitcase was not resolved," judge Masakazu Kamakura said.

But the court also heard Nelson failed to declare the bag was not hers, and stated her reasons for the visit were "business" instead of love, prompting the prosecution to label her "untrustworthy".

Nelson was smitten and was desperate to find a "respectable" man after her husband left her while she was pregnant with her fifth daughter, the court heard.

Her defence argued it was not abnormal for Nelson to become romantically involved with someone who lived overseas, given her own daughter married someone who was initially living in the UK.

They also pointed to Nelson's extensive community work, and her above average salary as chair of the Perth-based Aboriginal-run Derbarl Yerrigan Health Service which meant she had no reason to become involved with illicit drugs.

"I hate myself," Nelson admitted, after learning she had been involved in drug trafficking.

Donna Nelson claims she fell victim to a complex romance scam. (Supplied: Australian Greens)

Japan's legal system is distinct from Australia's.

Rather than a jury made up of civilians, the verdict was a decision for three professional judges and six civilians, known as "lay judges".

Japan also does not have a series of open court sessions before a trial, like Australia does, and Ms Nelson was barred from communicating with the outside world, excepting her lawyers.

The Japanese court did not accept Donna Nelson's explanation that she was the innocent victim of a romance scam. (Supplied: Yoshitaka Enomoto)

Japan has a 99 per cent conviction rate.

In sentencing her to six years' jail, the court ruled Nelson had already served 430 days in prison, which would be deducted from her total sentence.

Outside court, Nelson's lawyer in Japan Nishida Rie said her client would be appealing.

"I believe this was a very unreasonable decision," she said.

"We definitely need to talk with Donna but we will fight until then end, until she gets freedom.

'We strongly believe her innocence so we will fight until the end."

Ms Rie said Ms Nelson had checked the suitcase was empty.

Donna Nelson has been sentenced to six years in a Japanese jail. (Supplied: Derbarl Yerrigan Health Service)

"She cleared her doubt," she said.

"Even if she had some doubt, she cleared her doubt. That part, the court didn't actually answer, why they think there's still doubt over the suitcase.

"That's the most unreasonable part of their decision."

In a statement, Ms Nelson's family vowed to keep fighting.

"We are disappointed and devastated by the court's verdict in our Mum's case," they said. 

Kristal Hilaire said the family was putting on a brave face for Ms Nelson. (ABC News: Rebecca Trigger)

"We maintain that our Mum was the victim of a romance scam. She is the victim of a crime and not a criminal. She has always been against drugs. 

"As she said in her trial, she was duped — and did not know there were drugs in the bag her partner asked her to take into Japan. 

"We cannot say any more about the case at this time as we consider preparing for an appeal. 

"But we want to make clear now — we will never stop fighting for our Mum. And we will keep fighting until we can bring her home."

Daughter Kristal Hilaire spoke to her mother briefly after the verdict.

"I just said, 'It's OK, you're going to come home soon'," she said outside court.

Ms Hilaire said the sentence imposed was "far from lenient".

"You just have to look at how she looks now compared to how she looked when she arrived here. It's taken its toll on her," Ms Hilaire said.

"I worry about how she will handle another six years.

"As she was leaving, the one thing she crying said to me was, 'But my grandchildren'.

"And I know it's really hard for her having her grandchildren growing up and having birthdays and she missing out on their childhoods. And I want her home for that."