My girlfriend of a year and a half suddenly broke up with me.

She said she wasn't sure if she loved me anymore.

Her resolve was firm, and she wouldn't even hear me out when I pleaded for another chance.

Reluctantly, I broke up with her. In the midst of my heartbreak, her older sister—no, my *ex*-girlfriend's older sister—appears.

As events unfolded, when I explained the situation, my ex-girlfriend's older sister made me an unexpected proposal:

"How about you try dating *me* this time?"

Initially, the goal was to provoke my ex-girlfriend's jealousy, but I ended up spending such enjoyable days that the original purpose became irrelevant...

*Also posted on Kakuyomu with the same title.