Eiga Youkai Watch: Shadow Side - Oni-ou no Fukkatsu  

In ancient times, there lived an 11-year-old boy named Keita Amano, who possessed a wristwatch that could control Youkai. He befriended many Youkai and accomplished numerous deeds with their help. However, as he grew older, he lost his ability to see Youkai. Additionally, the wristwatch that controlled Youkai posed a threat to the balance between humans and Youkai worlds, so it was cast away into oblivion beyond time and space. Over time, the legend of the Youkai-controlling wristwatch faded away. But then, many years later, an epidemic known as Onimaro emerged, infecting people with malicious intentions and turning them into Kaodeka Oni. This caused chaos throughout the city. With the end in sight, only those chosen by a new Youkai Watch could stand up against the impending threat and save both Youkai and humans from certain destruction.