A young girl travels into a magical land to save her brother from real-world bullies...and from the evil King in Yellow. When her brother Hiroki disappears after a violent altercation with bullies, Yuriko finds a magical book in his room. She learns that Hiroki has been possessed by The Book of Heroes, and that only she can save him. With the help of the monk Sky, the dictionary-mouse Aju, and the mysterious Man of Ash, Yuriko has to solve the mystery of her vanished brother and save the world from the evil King in Yellow. When her brother Hiroki disappears after a violent altercation with school bullies, Yuriko finds a magical book in his room. The book leads her to another world where she learns that Hiroki has been possessed by the evil King in Yellow, and that only she can save him...and solve the riddle of why the King is also called "Hero."