A teenager from Aberdeen raped four girls including a 13-year-old.
Kyle Park has been jailed for six years following the attacks between 2014 and last year.
The 18-year-old raped the 13-year-old girl in July 2017 after she started to spend time with him when they began speaking on Facebook.
The High Court in Edinburgh was told Park befriended one victim after going on day trips organised by a social work department and they kept in touch.
After the attack, the girl got up and made to leave but the rapist punched her in the ribs and told her she was not to inform anyone about what had happened.
Judge Lady Wise said Park showed significant hostility to members of the opposite sex and was viewed as posing a high risk of sexual re-offending.
She said: “It is of particular concern to me that despite your young age you are already serving a period of detention in respect of other sexual offences.”
Park had previously received social work support for social, emotional and behavioural problems.