A 36-year-old man was sentenced Thursday to 18 years in prison for raping a woman aboard an express train in 2006.

According to the Otsu District Court, Takamitsu Uezono, a demolition worker from Shiga Prefecture, groped the woman, who was seated next to him aboard the Osaka-bound Thunderbird express on the JR Tokuriku Line on the night of Aug 3, 2006.

After threatening to kill her if she raised her voice, Uezono forced the victim into a men's lavatory and raped her, the court said.

According to a police investigation, none of the other passengers on the train tried to stop the assault or report it to the conductor, having also been threatened by Uezono.

Uezono was also convicted of sexually assaulting a woman on a local train on the JR Kosei Line, and another inside a lavatory at a train station in the city of Otsu on the night of Dec. 21 the same year.

"The crime was extremely contemptible . . . and the victim suffered enormous psychological pain," presiding Judge Yoshinobu Osaka said.

Prosecutors had demanded a 25-year sentence, arguing that someone who attacks in a public place is capable of repeating the offense.

In calling for leniency, Uezono's defense team said their client had committed the crime "under the influence of brain damage suffered" in a traffic accident.