In the world of high schooler Ryutaro Kanae, his creative spark ignites in the form of erotic novels featuring his best friend's younger sister, Suzune Minashizuki, as the protagonist. However, when Suzune stumbles upon his online works, a candid confrontation ensues. As Ryutaro confesses his unauthorized use of her as a character, Suzune surprises him with a bold proposition. Offering herself as inspiration for his writings, she dives headfirst into a whirlwind of suggestive scenarios, from exploring bare feet to delving into dom-sub dynamics. Thus unfolds a peculiar tale of taboo romance and mischievous antics between Ryutaro and his best friend's daring younger sister.