Even a dull guy like me has a girlfriend! I'm happy every day, but there's one thing that bothers me. That's the existence of my new sister-in-law! Why? She's jealous of my girlfriend, and she seduces me with a body and technique that's sexier than hers! The more I refuse, the more my sister-in-law gets Kokoro and escalates! Finally, she even inserts her dick and cums inside me...!? I feel sorry for her, but I can't resist the temptation of a grown woman... Because she has a great figure and is too erotic...