Onuma Mihono works at a travel agency. After breaking up with her boyfriend of six years, someone she had been thinking about marriage with, she realizes she is already 30. Then, a man transfers into Mihono’s company. It is Ureshino Eisei, the “accomplice” with whom, despite both of them having lovers at the time, she had a physical relationship 10 years ago. Mihono is shaken when Eisei speaks to her with a cool expression, but she resolves to treat him normally. However, when they are alone together, Eisei whispers in the same sweet voice as back then. “Don’t you feel like we’re destined?” The pleasure and desire that revive with their reunion. And yet, even after 10 years, she still cannot grasp his true feelings. Am I the one he truly loves? Or am I just for fun? Even as adults, unable to break free, she sinks deeper into a secret relationship.