Back in their school days, Riho and Touka shared mutual feelings for each other. However, due to a parental job transfer, they were separated almost immediately. Having lost all means of contact due to a mishap, the two spent over ten long years apart. Days went by without knowing where the other was, or if they would ever see each other again—
yet they never stopped thinking of one another. Eventually, both entered the workforce.

Amidst the rush of their hectic daily lives,
they felt the memories of the past slowly begin to fade away. Even so, they could never bring themselves to give up. For the two had once lived through a "strange tale" together. Knowing full well the importance of persevering and waiting,
they held onto faith that "one day, surely," and continued waiting for their reunion. During all those years unable to see Touka, Riho strictly cut off all involvement with the opposite sex.

When they finally reunited, getting together felt as natural as breathing. The time they spent apart transformed into a deep, unwavering devotion, and they began dating with marriage in mind. Riho came to dote on Touka even more intensely than before—to the point where she wanted to monopolize every single part of him. Having crossed into her thirties, her sexual desire had only grown stronger, and every ounce of it was completely fulfilled through her relationship with Touka. Everything was smooth sailing.

Between the two of them, there wasn't the slightest opening for another man to slip in. Just what on earth could cause the sail of Riho's reason to rip apart...?