Spiral of regression from dystopia / Dystopia / Spiral of dystopian regression.

Childhood friend, a girl with large breasts, a perverted uncle, dark summoning rituals and much more wrapped in a plot of saving yet another world.

 

 

"The main character, who was living carefree with his friends at the end of summer vacation, meets a girl who is looking for an ancient book. As far as I understood, the book is needed to prevent the destruction of the world. And as for the hentai, you'll find out by watching Rasen Sokou no Dystopia. The hentai is based on the plot of the visual novel of the same name."