The story on Arcadia's mystery, on which the 13th television episode was based.

The movie will feature special guests such as popular familiar characters from the TV anime series and the latest Youkai from the upcoming Youkai Watch 2 sequel games.

The four princes of Grannzreich—Kai, Bruno, Leonhard, and Licht— continue to compete for the right to their kingdom's throne under the guidance of their beloved royal tutor, the competent yet childlike Heine Wittgenstein. One day, during a political visit to Grannzreich, the king of the neighboring Romano Kingdom arrives at the royal palace with his twin sons, Ivan and Eugene. In the hopes of befriending the twins, Heine and the four princes meet their visitors, but their efforts are thwarted instantly when the two twin princes declare that they refuse to address those who will never reach the throne. Dispersing the tension between the boys, Heine reveals that he, upon their father King Victor von Grannzreich's request, will be tutoring the Romano princes alongside the Grannzreichs for the duration of their stay, in hopes of strengthening the future relations between the two kingdoms. [Written by MAL Rewrite]

Taking place 30 years after the events of the original Youkai Watch TV series. There was once a 11 year old boy named Keita Amano who held a wristwatch that could command Youkai, he would make friends with the Youkai and fulfill a great many deeds. But when the boy grew up, he lost his ability to see Youkai. And as for the wristwatch that could control Youkai, its existence threatened to disturb the balance between human and Youkai worlds, so it was cast away into oblivion beyond time and space. Soon ... the story of the Youkai controlling wristwatch became but a legend. But then, something took place after many, many years had passed ... an epidemic Youkai virus known as Onimaro started affecting people with malevolent intentions and is spreading indefinitely, turning them into Kaodeka Oni and causing chaos throughout the city. With the end near, only the ones chosen by a new Youkai Watch can stand up against the upcoming threat and would save both Youkai and humans from certain destruction. (Source: Wiki)