A 55-year-old mother was arrested Jan. 29 on suspicion of forcing her son's teenage girlfriend into prostitution.

The Tokyo woman used Twitter to arrange for the girl, who was then 17, to have sex on more than 20 occasions, according to police.

The suspect has rejected the allegations, saying, “The girl did it on her own,” police said.

According to investigative sources, the teenager had fled from her own home and moved in with her 18-year-old boyfriend and his mother, the suspect, in Nerima Ward. The mother allegedly ordered the teenager to have sex with strangers arranged via Twitter, saying, "You should earn your own living expenses."

In one instance, the girl met a man in his 50s at a hotel in Tokyo’s Toshima Ward in December 2016, police said.

The police have sent papers on this man to prosecutors as he is suspected of infringing the law banning child prostitution and child pornography. The woman allegedly received 45,000 yen ($414) from the man.

It is believed the mother gained about 700,000 yen in total by arranging for the girl to have sex between December 2016 and January 2017. The incident was discovered when the girl, who is now 18, moved out from the home of the suspect in February 2017, police said.

The woman was arrested on suspicion of violating the child welfare law.