After a traveling sales merchant from China stops by the Cat Cafe on his usual stop, Shampoo grows interested in an item he has called 'The Red Thread of Fate.' If the thread is tied around the pinky fingers of two people and kept so for 5 hours, the thread will disappear and the two will be matched for life.
Shampoo eventually gets the thread tied around hers and Ranma's pinky fingers, the result of which Ranma becomes madly infatuated with her, much to Akane's displeasure. When it is announced that Ranma and Akane are intended to be married as soon as possible, Ukyo, Mousse and Kodachi attempt to interfere, along with Ryouga.
Akane attempts to pretend that it doesn't matter to her who Ranma marries, but when her sister Nabiki explains how Ranma is simply marrying Shampoo due to the red thread attached to their pinky fingers, Akane sneaks into the wedding ceremony. Pretending to be there on friendly terms, Akane manages to sever the red thread before the full effects take place.