After fighting with her boyfriend, Mami, the younger sister, rolls into her older sister's place. She encounters her sister's boyfriend for the first time. Playing a prank on her sister's seemingly shy and serious boyfriend ignites his lust, leading to repeated sex from that day forward. Discovering he can ejaculate multiple times without tiring, she finds herself relentlessly fucked with piston-like thrusts that destroy her pussy, leaving her filled with regret!
