Yuya Takase was in his third year as a working adult, having joined an exploitative "black company," and was leading a demanding life filled with work.

Exhausted by a daily routine consumed by work and devoid of any personal time, Yuya found himself on Christmas Eve night. On his way home from work that day, weary of life and contemplating suicide, he coincidentally reunites with Ema Suzukaze, his fated childhood friend who had suddenly transferred schools ten years ago.

In her first year of high school, Ema had been a breathtaking beauty with an excellent figure, admired by all, and Yuya had believed her future was secure. Yet, for some reason, she was now living at home and working part-time at a convenience store.

After their lively conversation upon reuniting, as Yuya, concerned for Ema, was walking her home, they were suddenly attacked by an assailant and both were killed.

But when Yuya next awoke, for some reason, he and Ema had time-leaped back to when they were high school students.

Yuya was bewildered by the sudden turn of events, but Ema, claiming she didn't care if it was a dream or reality, made a proposal.

"Since we have this chance... why don't we try reliving our youth and falling in love, together?"

Following Ema's sudden proposal, Yuya and she begin to relive the time they had lost.

As Yuya enjoys his time with Ema, he comes to learn the circumstances behind her transfer in the summer of their first year of high school—

This is a story about two people who, after reuniting as adults and confessing their past feelings for each other, return to the past and fall in love once more.