Given the information, it seems you're likely referring to an anime or a manga that involves an elf character and possibly themes of addition, books, or learning. Without more specific details, it's challenging to pinpoint exactly what you're referring to.
Caption: “A new seal, a new destiny.” elf ni inmon o tsukeru hon the animation new
Below is a detailed write-up for the animated adaptation. Given the information, it seems you're likely referring