The Red String of Fate is a crimson thread attached to a person's left pinky finger. Those who possess this thread are destined to be connected to and eventually united with another specific person. Conversely, those without a thread are destined never to marry, or their fated partner is in a place far beyond their reach.

This Red String of Fate can be easily severed using tools like scissors, but once cut, the connection to that partner is lost forever. Alternatively, by wrapping the thread around the pinky of a desired person, one can force a fated union. However, the act of cutting the thread can only be done once; after it is cut and reconnected, the fated partner can never be changed again. By actually seeing the fated partner one is connected to, feelings of love gradually amplify.