Police arrested the four on suspicion of crimes including extortion. The 27-year-old opthalmologist, Shintaro Okui, was also arrested on suspicion of violating the Anti-Child Prostitution and Pornography Law after he informed police about the youths' actions, law enforcers said.
Investigators said the 17-year-old girl conspired with her 18-year-old high school boyfriend and two other friends to extort money from the doctor.
In July this year, they approached him on a road in Tokyo's Shibuya-ku, and started an argument with him, saying, "Why did you touch someone else's girl?" and extorted 130,000 yen and a watch costing about 1 million yen from him, police said.
Also arrested with the 17- and 18-year-old students were a 19-year-old correspondence school student and an unemployed 16-year-old youth. The names of the four have been withheld because they are minors.
Okui is accused of handing the 17-year-old girl 10,000 yen and engaging in indecent acts with her at a hotel in Tokyo's Shinagawa-ku in September 2005. The incident reportedly came to light after Okui went to Shibuya Police Station to inform police about the extortion.