My girlfriend kept having sex with her sister until she cummed inside her while she was traveling. (Matsushita Saeko, BF-567)

My live-in girlfriend is going on a family trip for four days. Her older sister, Saeko Matsushita, who can't go because of work, suddenly shows up at my house. Ignoring my annoyance, she starts seducing me... and we go at it like crazy for the four days my girlfriend's away!