At a certain point in time in Japan, a strange phenomenon suddenly occurred in which all literary books were stained black. This was a disaster caused by the "eroders" born with negative emotions in the books. The eroded literary books will gradually disappear from people's memories, and finally become as if they had never existed from the beginning. Therefore, the "alchemist" with special abilities was sent to the library as a special agent librarian to fight against the "eroder" who destroyed the world in the book and to protect literature, and fought together with the reincarnated literary masters.