twelve-year-old boy is arrested for purse-snatching (which he actually
didn't do; the purse was dumped in his hands by the fleeing criminal).
He is a homeless orphan, with no identification. He has no surviving adult relatives. Assume he is able to convince them of his innocence. What will happen next? Will the police keep him under arrest while looking for his parents? Will he be put in foster care? Released? How long will it take?
Searched for "japan juvenille arrest procedure", "japan child law", etc. Found out there is a seperate court system and police have broad discretion with delinquients, but no procedural details.