There was a national library which possess well over fifty million books in a town named Durvel. A girl named Noemi was working as a librarian in the national library. One day when she is building a database of the book a national library possess with her colleagues, strange voice has been heard from the direction in the stacks prohibited. She entered the stacks prohibited to make sure of the true character of the voice. And she patrolled around the stacks prohibited cautiously while saying “Is there anyone? Do not hide and come out”, but there was no one. One thick book fell suddenly at her feet. <The book of seals> was recorded by a form like Fraktur on a cover of the book. She opened the book, much black shadows were released from a book. And a big dog with three heads emerged from a book and boarded a bookshelf. She was surprised and screamed. Then her colleague named Vihar worries about her and has run. Vihar asked “What happened?” “Here is restricted” Noemi pointed to the bookshelf on which the big dog with three heads gets to the top. The big dog with three heads said “Only you see my figure” Vihar said “There is norhing” Noemi said “It was my imagination” Noemi pointed to a book and said “Strange voice has been heard from the stacks prohibited, so when I come to the stacks prohibited, this book has fallen suddenly” Vihar said “This book is not the book possess in a stacks prohibited” Noemi asked “Eh?” “May I take this book?” Vihar said “I think that is no problem because that is not a book here” She has picked the book up and has gone out of the stacks prohibited with Vihar. The big dog with three heads has followed behind her and has gone out of the stacks prohibited. And when she is building a database of a book again, a scream has been heard from the neighbourhood of the national library. Noemi asked “Who are you?” The big dog with three heads said “I am a watchdog named Cerberus of <The book of seals> you have now” Cerberus said “Devils are sowing the seeds of discord on all part because you broke seals” “You have no choice but to seal devils into this book up” Noemi asked “What should I do?” Cerberus said “Because I make a devil weaken, you intone the incantation recorded on the book” Noemi said “Ok” When she opened the book, <Deabruak nor lo ibiltzen liburu honetan!> was recorded on a book as sealing method. Cerberus said “Get on my back!” She held a book and sat astride a back of Cerberus and they went to the devil. A flame, a chill and thunder were thrown for a devil from the respective mouths of three heads of Cerberus. She opened a book and intoned “Deabruak nor lo ibiltzen liburu honetan!” Then the devil was swallowed up in the book. And they sealed devils up one after another. When they finish sealing all devils up, Cerberus said “I get to sleep in the book” and disappeared. Cerberus which entered in the book appeared in a cover. She hid the book in the place found by no one in a stacks prohibited.