Jeong Hae-deun, a former competitive swimmer now working at a swimming center, is tricked by Han Si-oh's cruel lie—that a leg injury has ended his career. Compassionate Hae-deun lets him move in, unaware that Si-oh has harbored feelings for him for a very long time. Seizing the opportunity, the obsessed Si-oh wastes no time in his relentless pursuit, his desires escalating from subtle flirtation to outright aggression. The game changes when Si-oh reveals his true, dark intent: "I want to spend all day kissing and biting you, I want to fuck you, Hyung... I want to fill your inside completely with mine."