TOKYO >> A Chinese movie actor has been arrested in Japan on suspicion of assaulting his then-girlfriend, causing injuries that police say required four weeks of treatment.

Jiang Jinfu, 27, was detained Wednesday after he turned himself in at a central Tokyo police station, police confirmed today. Authorities already had an arrest warrant for him after a 25-year-old woman filed a complaint about the alleged assault, prompting an investigation.

Jiang, who is known for his leading role in the 2012 film “Xuan-Yuan Sword: Scar of Sky,” apologized to his followers on the Weibo microblogging service, saying in the Nov. 20 post that he had been living in remorse and felt ashamed about his behavior, adding that he would take responsibility and accept the punishment.

His arrest has caused a storm on social media in China. Several Chinese celebrities described Jiang as warm and sincere, and some said they would wait for the truth to come out, prompting outrage and discussion of violence against women.

According to police, Jiang allegedly beat her on the face, arms and shoulders on Oct. 12. The couple lived together at his Tokyo apartment at the time but then apparently broke up, police said. Japanese media have reported that Jiang has been in Tokyo since April to study Japanese.

The South China Morning Post newspaper in Hong Kong identified the woman as Japanese model Haruka Nakaura. She posted her own photos purportedly showing bruised cheeks and upper arms on Instagram.

Japanese police refused to identify the woman, citing privacy.