Riko, a young, curious woman, finds herself alone with her stepbrother, Ta, in their cramped apartment. As they bicker and tease each other, Riko's eyes linger on Ta's toned body, and she can't help but feel a stirring in her loins. Ta, equally affected, watches as Riko's nipples harden under her thin shirt. Their arguments turn into heated debates, and soon, they're both panting, the air thick with sexual tension. Riko, unable to resist, reaches out to touch Ta's bulging crotch, and he responds by pulling her close, their lips meeting in a passionate, forbidden kiss.