On a cruise, Shinchan's adult family members are nabbed by a bunch of monkeys and held on a mysterious island as slaves for an evil jungle king.
A grownup Shinchan sends Tamiko on a mission to bring his five-year-old self to the time period right before he is captured.
They also meet a mysterious girl named Saki who is somehow connected to these dreams.the Kasukabe Defense Group to save their dreams and escape from the nightmare world.
When the five visit a private academy, Kazama is attacked, and left with reduced intelligence and strange bite marks.