The protagonist Erika Fleur wakes up one morning and notices that a book on her shelf is glowing brightly. The book was a collection of nursery rhymes called ‘Mother Goose’ and it was given to her by her grandmother when she was small, but Erika had forgotten all about it. Since its glowing, she opens it and suddenly finds herself in a mansion surrounded by five men who introduce themselves as the inhabitants of the book. They and the owner of the mansion, Mother Goose, thought that everyone forgot about them, so Erika has to take exams about nursery rhymes in order to return to her world.

[Edited from 4 Shiki]