Yuri has been married for five years. She's a woman of many hobbies and surprisingly active, contrary to her appearance. Recently, she's been really into running, participating in marathons and other races. One day, while running as usual, Yuri accidentally falls and injures herself. The man who comes to her rescue is the man who will later become her lover. Because her husband usually treats her like a housekeeper, his gentlemanly and kind demeanor moves her heart, and she crosses the line. Then, consumed by her desires, Yuri embarks on a secret affair trip…