Due to their father's work, elementary school brothers Kenta and Yuuki are temporarily staying at their younger uncle and aunt's house. They become captivated by their aunt KAORI's beautiful, glamorous figure. One night, as Kenta returns to his room from the bathroom, he accidentally witnesses KAORI and his uncle happily engaged in a tight bondage session in their bedroom. This shocking scene sparks Kenta's curiosity about BDSM. Using his childlike innocence to his advantage, he skillfully draws closer to his aunt. What begins with simple handcuff restraint gradually escalates—Kenta starts using ropes, eventually involving his younger brother, until the big-titted married woman becomes completely submissive to the dual boy cock domination. The story unfolds with an unusual dynamic where a boy's pure curiosity intertwines with adult temptation, creating a compelling and twisted relationship.