Kary and the blue paint

Apparently there was now a secret ninja school in Jons home town and one of their exams is to use stealth to mark someone while wearing bright colored cloths.
People who he went to school with could secretly be a ninja.
"Hmm, that's kind of cool actually" Jon said to no one "I wish I knew that ninja's identity"
The knowledge entered Jons mind that the ninja was Karyn