The girl was detained by police for chalking a flower on the "Lennon Wall", a staircase at the main Admiralty protest site which became plastered with brightly-coloured notes of support for the democracy movement during more than two months of rallies.
Notes and messages have sporadically been posted on the wall since the protest sites were cleared earlier in December.
The teenager was arrested in the early hours of December 23 after scribbling on the wall and was detained for 17 hours, said solicitor Patricia Ho.
The girl has been in trouble with police before, said Ho, but she added that there was "no evidence to say that she is not well taken care of" at home.
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In a separate case, a 14-year-old boy could also be removed from his parents following his arrest as police cleared the Mongkok protest camp in late November.
"These types of orders are usually sought in extreme cases, for example the child is on drugs, or trading drugs, or prostituting themselves," Ho told AFP.
"It's a very worrying trend... It's imposing a climate of fear."
The magistrate at Monday's hearing deemed it safer for the teenager to go into a girls' home, Ho said. The application before the court alleges that she is being neglected by her family.
But neither the girl nor her father wanted her to be removed, Ho said.
"She was very upset and said she was afraid of going into the home," in a statement to the court, said Ho.
"He said he would want to go wherever she goes," said Ho.
A social worker will investigate before the next hearing in January, Ho said.
The next hearing in the teenage boy's case will also take place in January.
Neither has been charged since their arrests, said Ho.
Police were not immediately able to comment on the cases.
Minors were arrested during the mass protests for fully free leadership elections and at subsequent smaller gatherings.
Police told AFP that they do not have a total figure for the number of minors detained in relation to the demonstrations -- but some as young as 13 were arrested at small Christmas protests in Mongkok, according to police statements.