Kana Miyawaki, an office lady who holds a position with responsibility and devotes herself to work every day, has an unforgettable man who is the reason why she can't start a new love. Sohei-kun, whom she met at an intercollegiate circle when she entered university, is flirtatious and kind to girls. “Until you get tired of it, will you be my sex friend?” My first love, with whom I had a young relationship and broke up without telling my feelings for him. One day, Sohei comes to the next department as a new employee! ? Kana is perplexed by Sohei's grown-up appearance, but Sohei stares at her with a passionate gaze like he used to, reminding her of "those days"... "-Kana, you've always been good at inviting me."