"I'll make you realize just how much I love you." She is kissed so deeply she can barely catch her breath, as her younger boyfriend pours a decade's worth of pent-up longing into every touch. Hiyori Matsuki is a late-twenties office worker at a major firm—gentle, serious, and wholly inexperienced with men. When she finds herself on the verge of trouble during a group date, a younger man named Reo steps in to save her. But strangely, he seems to already know her... "I've loved only you for the past ten years." So begins a suffocatingly intense, obsessive love story with a clingy younger boyfriend.