One day, red threads appeared on the fingers of all humans worldwide. Since those bound by that thread were destined for lasting relationships, it became known as the "red thread of fate," and a new era dawned where thread-based romance became the norm. While all this was happening, a red thread suddenly appeared on the finger of the protagonist, Tsumugi, who, incidentally, just happens to despise "thread-based love"....

(Source: Manga Park, translated)