Lost in Fantasy: It's Okay If It's Only in My Imagination, Right?

Nako is ga―ga for her handsome little stepbrother, Mizuki. In addition to wanting to protect and take care of her brother, she finds herself swept away by urges to play out one sensual situation after another with him in her imagination. Although she's been able to maintain a proper, sisterly distance, an unforeseen turn of events finds the two of them temporarily living together. Will Nako still be able to keep her cool with her darling brother sleeping in the next room over? A playful love story between a woman with an overactive imagination and her college student brother.