Ranma Saotome in his Female form was taking a walk within town with little notion that he was about to meet some unexpected characters. Such as Ataru Moroboshi who believes Ranma really was a girl tries to get her e-mail address and a date. Lum Invader, who was informed of a special gathering that was happening within the town. It wasn't long until Inuyasha and Kagome show up and when all five characters meet each other, it leads to a series of misunderstandings and fights.
The characters from Ranma 1/2, Urusei Yatsura, and Inuyasha all gather together in a short crossover to introduce the 50th Anniversary Weekly Shonen Sunday "Rumic World" Museum opening, celebrating Rumiko Takahashi's manga work.
Ataru e gli altri si uniranno al concorso di 'Corsa di nuoto ad ostacoli', organizzato dal Preside della scuola superiore Tomobiki. Ciascuno degli studenti del Tomobiki devono affrontare diversi tipi di ostacoli durante la gara, solo pochi di essi raggiungono la finale e la loro situazione sta diventando sempre più dura e più difficile rispetto agli ostacoli precedenti.
