A man with a fetish for Ugg boots has admitted using the internet to harass a group of schoolgirls in the Leeds area.
Mark Southeby, 38, used social networking sites to contact the girls.
An "enormous number" of photographs of teenage girls wearing the boots were found on his mobile phone, Leeds Crown Court heard.
Southeby, of Dutton Way, Iver, Bucks, also developed an online relationship with one 15-year-old and tried to goad her into a series of sex acts.
Southeby, who is unemployed, admitted three counts of inciting sexual activity involving the same 15-year-old girl and six offences of harassing teenage girls.
The court heard the married stepfather infiltrated a group of girls at a secondary school in the Leeds area by posing as their friends using fake email addresses.
Southeby's lawyer told the judge his client recognised he had a problem which needed treatment and "were it effectively chemical castration, that would be a benefit".
The court heard Southeby's contact with the girls lasted from July last year until his arrest in December.
He became particularly obsessed with one 14-year-old girl, the judge was told.
Robin Frieze, prosecuting, said: "He [Southeby] was particularly interested in Ugg boots, which he later told police he had a fetish about."
The court also heard Southeby had built a relationship with a 15-year-old girl who eventually believed they were boyfriend and girlfriend.
He asked her to perform a series of sex acts but she refused.
Southeby's harassment of five other girls included phoning one teenager 36 times.
The court heard he had never met any of the girls in person.
Judge Jennifer Kershaw adjourned sentence until Monday.