Actor Yuta Takahata, 22, was released on bail from Maebashi Police Station in Gunma Prefecture on Friday after prosecutors decided not to pursue rape charges over an incident involving a hotel worker in the city.
"I am truly sorry," Takahata said as he bowed his head in apology before media reporters gathered at the police station.
Takahata reportedly settled the case with the victim, which led prosecutors to drop the case.
Police say Takahata admitted raping the woman, telling them he "couldn't control" his desire after looking at her. The victim, in her 40s, sustained injuries.
The son of popular actress Atsuko Takahata, Yuta is one of the young stars of Japanese showbiz, with regular TV appearances and movie roles.
Police say Takahata attacked the worker in his room after returning from drinking.
Investigators said Takahata asked the employee to bring him a toothbrush and then pulled her into the room around 2 a.m. on Aug. 23. He allegedly pinned down her arms and legs during the rape.
At around 3:30 a.m., an acquaintance of the victim alerted police.
Takahata has been staying at the hotel since Aug. 21 for a film shoot.
He reportedly went out drinking with staff but is not thought to have been drunk at the time of the incident.