Here is the summary for The Flower of Death and the Glass Keys, the sequel to The Runaway Magician and the Lost Prince and book 2 of the Runaway Magician series:
A dark deal… Ten glass keys… An academy of magic… For three long years, the empire of Doryoku has been terrorized from within by a deadly assassin called the Manjusaka, talked about only in hushed whispers. Little do the empire’s citizens know that their most feared enemy is a sixteen-year-old boy who lives in the slums and sleeps in a shack. When Spider Lily is offered a once-in-a-lifetime chance for money, he can’t refuse it. All it entails is going to Adamas Royal Magic Academy and spying on the crown prince of Doryoku, Fuyuuki Hononen. But someone is out to kill all of the nobles of the academy, including Fuyuuki, so Spider Lily will have to use all of his assassination knowledge to protect his target, lest he loses his chance forever.
