The four older sisters remain true to their identity as purebred black gyarus, thrust into intense situations in their daily lives. With their parents away on a trip, they're left alone to get through the day, relentlessly targeting their younger brother with overwhelming energy. He's pushed beyond his limits, forced to endure countless waves of pleasure, yet the gyaru sisters show no mercy—driven by an unshakable determination to pull him down into their world. Their fierce passion and unwavering strength elevate the story's intensity.