Koi steps onto the bullet train, her demeanor tinged with nervous anticipation. Though her married life holds no dissatisfaction, she admits that the once- or twice-weekly sex leaves her craving more—she desires a purely physical relationship with another man. It's surprising to hear such words from someone with her typically demure personality. Once the remote-controlled vibrator is inserted, her latent masochistic tendencies awaken, her body responding intensely and quickly becoming wet and aroused. In the act of sex with a man she's just met, both her mind and body sink completely into pleasure.