Rin cannot satisfy her boyfriend, her younger brother's passive partner in bed. However, his older brother is a well-endowed man who gets instantly aroused at even the slightest kiss, always eager for sex. Subjected to his relentless, passionate lovemaking, Rin's desire intensifies rapidly, and her feelings gradually shift from the younger brother to the older one. Unfulfilled in her relationship with her boyfriend, Rin finds a new romantic connection forming through her growing bond with his brother.