Kaoru Sugimura, a seventeen-year-old with a fondness for sadomasochism, finds solace in mastering erotic knots and maintaining his collection of gear. Despite his expertise, he longs for a partner to explore his array of items. His heart is set on Nana Chigusa, his childhood friend and the esteemed vice-president of the school's student council. However, their friendship has deteriorated over time due to their differing priorities—Kaoru's indulgence in his fetish at the expense of academics clashes with Nana's academic dedication. Concerned about Kaoru's distractions, his mother discreetly entrusts Nana with some of his S&M paraphernalia. Curious, Nana tries on a leather costume but accidentally gets stuck, requiring Kaoru's assistance to free her. Surprisingly, this experience opens Nana's eyes to the stress-relieving nature of S&M, leading her to seek further exploration with Kaoru, much to his delight.