Three judges in a Japanese court have sent the 19-year-old suspect in the Nicola Furlong murder case forward for trial in the criminal courts, which will treat him as an adult.
The penalty for murder in Japan is life imprisonment.
If the 19-year-old suspect had been tried as a juvenile, he would have faced the possibility of a maximum of five years in prison if convicted.
Reporting restrictions in the case will now be eased.
The judges made their decision based on victim impact statements from Ms Furlong's family and police reports into the case.
The defendant, who is a musician from the US, is charged with strangling Ms Furlong to death in a Tokyo hotel in May.
The 21-year-old Wexford woman was in Japan as part of her studies with Dublin City University.
A source in the Tokyo Public Prosecutors' Office said he could not predict when the trial would begin, but the start is likely to be months away.
The Furlongs, who fly home to Dublin tomorrow, have pledged to return to Tokyo.
Angela Furlong, Nicola's mother said it was very "daunting coming out but we're glad we did".
Nicola's father said: "We're certainly coming back if it comes to trial".