The 25-year-old, who was booted out of the Asian Games in Incheon and slapped with an 18-month ban by the Japan Swimming Federation, said he had confessed because he feared he would not be allowed to return home.
He also claimed that the poolside security camera footage Korean prosecutors said showed him taking the $7,600 camera was unclear.
"I didn't steal the camera," Tomita told a news conference in Nagoya, claiming an unidentified person had grabbed his arm and placed a "black object" in his bag.
"Maybe my heart was weak," he added, tears rolling down his cheeks.
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"I shouldn't have confessed. The police showed me pictures of the security cameras only on a smartphone and the images were very rough and blurred. They didn't show me taking a camera."
Tomita's lawyer, Bujiro Kunita, said Korean police had fabricated the charges and had used an interpreter with insufficient Japanese. He suggested the real culprit had been someone with a vendetta against the Japan swimming team.