Nicola Furlong's family have said their daughter’s life was worth more than the five to 10 years in jail her killer will serve.
US musician Richard Hinds, 19, from Memphis, Tennessee, was found guilty of killing 21-year-old Nicola Furlong in a hotel bedroom in Tokyo on May 24 last year.
A court ruled that he had strangled the exchange student with a towel or tank top in the Keio Plaza hotel in the city’s Shinjuku district.
Ms Furlong’s mother Angela said: “Nicola’s life was worth more than that.”
She added: “It’s good that they (judges) cleared her name. Nicola has done nothing wrong. It was all him and his lies that brought us out here.
“We still don’t know the truth of what happened in that room but we know Nicola did nothing wrong, we knew that coming out anyway.”
Hinds was on trial as a minor. The death penalty was not an option for judges and possible sentence was limited to up to 10 years.
Nicola’s father Andrew said the family had been made aware that possible sentences were limited.
“When we found out he was on trial as a minor we knew it was not going to be a hanging,” he said.
Hinds stood silently as he was found guilty of strangling the student in what the presiding judge called a “vicious” attack.
His evidence was also described as at times not credible, and irrational.
The court ruled that Hinds had tried to taint Nicola's memory and that he had shown no remorse.
Hinds and another American were accused of taking Nicola, 21, and one of her friends to the hotel after they had passed out in a bar.
The Tokyo District Court ruled that Hinds strangled Nicola to keep her quiet when she regained consciousness in his hotel room.
A second American man, James Blackston, a 23-year-old dancer from Los Angeles, was seen with Hinds bringing Nicola and her unnamed friend unconscious into the hotel on CCTV footage which was played to the court.
He was convicted last week of sexually assaulting the second girl and sentenced to three years in jail.
Nicola’s sister Andrea said she felt let down by the Japanese criminal justice system.
“I’m absolutely disgusted and so angry and so hurt,” she said. “We had so much faith in the Japanese doing justice four us and I don’t feel we got it.”