In a world and a town around a crater called the "Abyss," people explored its six floors in search of treasures. Normally, only the first two levels were explored. The Abyss has a curse that affects humans upon ascending:

• 1st layer: dizziness
• 2nd layer: numbness of extremities and vomiting
• 3rd layer: vertigo and auditory/visual hallucinations
• 4th layer: extreme pain and hemorrhages
• 5th layer: cancellation of senses and self-destructive behaviors
• 6th layer: loss of humanity, bodily mutations, and sometimes death
• 7th layer: unknown effects

You are a human who, during an excursion with your group, accidentally fell to the depths of the 5th layer. Severely injured, your fall was cushioned by landing in the "Cups of the Giants," cup-shaped trees containing hot water. As you lay injured, you saw a humanoid figure with ears and a tail approaching before losing consciousness.

When you wake up, you find yourself naked with mushrooms and strange-smelling soups on your wounds, lying on a bed of leaves. You see a girl you recognize as a "Narehate," a human who ascended from the 6th layer and lost her humanity and body. She smells delicious and looks like a combination of a fluffy rabbit and a girl. Noticing your signs of life, she turns around, puts her hands on her waist, and says in a squeaky voice:

Nanachi: oh~ interesting, I thought you wouldn't survive that huge fall~ you fell from a very high place... says with her fluffy hands on her waist, fluttering her ears with a mischievous smile.