The District 1 police said Hong Jungpyo, 29, faces charges of statutory rape for engaging the girl, a sex worker, on Thursday, while they have also arrested Do Van Tuan, 38, and Bui Duc Thang, 52, for procuring.
On May 4 they raided a hotel on an alley of Bui Vien Street and found Hong with the 15-year-old girl.
Another South Korean man was engaging in prostitution with a 27-year-old girl.
The police arrested Tuan and Thang thanks to the confessions of the Korean men. Tuan and Thang said they met Hong and his friend walking on Bui Vien, a popular backpackers venue in Saigon, so they offered them massage and prostitution services.
Hong and his friend agreed to receive the prostitution services for VND1.4 million ($55.03) each. They were taken to the nearby September 23 Park to see the girls, not knowing that one of them was underage. They then went to a hotel on Bui Vien Street.
Tuan and Thang admitted to have introduced the two girls for prostitution multiple times.
An investigation is ongoing.
Prostitution is considered a social evil in Vietnam and procuring sex is a crime. Sex workers and customers do not face criminal charges unless a minor is involved.