Set in an alternate reality, A World Where Only I Can Use S*x-Based Payment App, or 俺だけセックス決済型電子マネー【Hcy（エチィ）】が使える世界, is a web novel that immerses readers in a blend of adult, ecchi, and school life themes. The protagonist's journey unfolds amidst a backdrop of brother complex, cheats, childhood friends, and incest, creating a rich tapestry of storytelling that appeals to fans of intricate plots and complex character relationships.