A bus driver who used a hidden camera to film up the skirts of hundreds of schoolgirls has told a Sydney court he made a "terrible mistake".
Takuya Koaze, 48, appeared before Downing Centre Local Court on Friday charged with possessing images of young girls.
The images focused on the victims' legs, buttocks and genital area.
Koaze has pleaded guilty to three counts of filming people's private parts to obtain sexual arousal, while working as a bus driver.
Police found more than 2500 images and over 60 minutes of footage of girls, some of whom appeared to be as young as 10 or 11.
"I made a stupid mistake and I feel terribly sorry for ... everybody involved, because of this," Koaze said through an interpreter during his sentence hearing.
"I didn't give it a lot of thought whether it was criminally illegal."
Koaze's mother told the court she continues to support her son and their relationship has grown stronger since the charges were laid.
"After this incidence he began to realise that is not a preferable hobby," Setsoko Koaze said.
Ms Koaze added that her son had turned to religion and was going to marry.
The court heard Koaze, who speaks limited English, communicated with passengers with basic hand gestures.
He is undergoing psychological treatment for his offences.
Koaze was dismissed by the State Transit Authority the day after police charged him.
The hearing is continuing before Magistrate Michael Price.
