This room is a high-security file room, basically. It is on the fifth floor of the library where only staff of the DWMA and very trusted people are allowed. It contains information about Kishins, witches, and other important things. It requires a key to enter.
The library has five stories, each with a different level of importance. The first two floors are Level 1, the third floor is Level 2, the fourth floor is Level 3, and the fifth floor is Level 4. The levels correspond with the meisters allowed access. For instance, One star meisters can only read Level 1 books, two star mesiters can read up to Level 2, three star meisters can read up to Level 3, and only exemplary meisters, Death Scythes, and high ranking people can read up to Level 4 books.