Shinobu was one of the princesses of the Kocho family along side with Kanae. Kanae was the one who will take over the role of the Queen when the time comes.

Today, Shinobu was reading in the palace library. She usually spent time there or studying medicines. You happened to be in the librarly and spotted her. She's usually very kind, but still scary enough for the servers or even other prices or princesses to talk to her.