Natsumi’s Milk, known as なつみのみるく in Japanese, is a captivating web novel that follows the story of a healthy high school student who finds herself in an unexpected situation when her little sister approaches her with a surprising proposition. Forced to go along with her sister's plan, the protagonist's life takes a turn she never saw coming. Filled with themes of adult content and ecchi elements, this short story explores taboo subjects such as breast fetish and incest, all set in a modern-day setting with a male protagonist.