"If you are a fan of series like “That Time I Got Reincarnated as a Slime” or “So I'm a Spider, So What?” this book is worth a look-see."
Death and Reincarnation.
Kuroe Makoto, the tomboyish ace of her high school track and field club, never spared a thought for these things before. However, when she falls asleep in her Tokyo home after an exhausting marathon and wakes up in a fantasy world, those concepts become her reality. And unlike in the common light novel setting, she isn't reincarnated as the naturally good-looking and talented human hero who gathers a harem effortlessly.
In fact, she isn't reincarnated as a human at all. She is reborn as 'Chaos', child of the demon queen and heir to a kingdom at war with humanity.
Demon Princess Magical Chaos puts the Japanese high school girl in a tentacle monster, in this strange tale of a sound human mind possessing a horrifying creature's body.
Join Chaos on her oftentimes humorous but also perilous journey through a world of sword and sorcery, as she discovers a newfound appetite for life, terror, and demi-human girls.

This is the first volume in a series of eight books.
Reader thoughts:
"An amazing storyline enriched with delicious humor, wrapped with a unique style of writing that resembles a well-translated light novel." ★★★★★
"Found myself drawn in as if a tentacle wrapped around my ankle and pulled me into a dark abyss." ★★★★★
"Good language and writing style, well-designed characters - it's a damn rare thing in this sort of books for characters, even secondary ones, to outgrow their assigned plot role in terms of personal complexity." ★★★★★