20th century, Yoshida Village, Shimane Prefecture. Local elementary school student Yoshida-kun and his friends, playing in their secret base, are visited by time-traveling agents Morelder and Nascary from the World Federation Investigation Bureau's X Division, who have come from the future. Together, they begin searching for the "Cursed Video" said to be causing mysterious incidents in their time. However, their path is repeatedly blocked by one mystifying event after another—UMA (Unidentified Mysterious Animals), out-of-place artifacts, supernatural phenomena—all irresistibly tempting diversions! How will Yoshida-kun and his friends' great adventure conclude...?