There is no anime with this exact title. However, the query strongly points toward a specific 2018-2020 trend of adult fantasy anime based on "curse mark" or "slave crest" doujinshi (self-published books).
Back in her chambers, a cozy, secluded glade deep within the forest, Eira opened the book. The pages, filled with diagrams, symbols, and text that seemed to change and rearrange themselves as she read, spoke of ancient powers and forbidden knowledge. It became clear that this was no ordinary book; it was a guide to unlocking and enhancing one's magical abilities. elf ni inmon o tsukeru hon the animation verified
Elf ni Inmon o Tsukeru Hon The Animation (also known as Elf ni Inmon wo Tsukeru Hon There is no anime with this exact title
The book, bound in a strange, pulsating material that seemed to shift between black and a deep, iridescent blue, caught her eye. Its title, "Inmon o Tsukeru Hon" or "The Book that Gives You a Bonus," was etched in gold letters that shimmered with an otherworldly light. Despite the intriguing title, the book was not in Eira's native Elvish, nor in any language she had seen before. The pages, filled with diagrams, symbols, and text
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