Isn't It Normal for a Librarian to Have Tentacles?

The girlfriend who passed away for unknown reasons left behind strange relics, whispers came from the closed fourth floor of the library, half-fish, half-human creatures crawled out of the sea, and rotten dragons soared in the night sky. They seemed to be everywhere. A clear-minded college student accidentally obtained a notebook called Daoxuan Shanggan. This is the possible change in his body.