A young boy plays in the hospital room of his mother who is about to have a baby. After the father dejectedly leaves, the room suddenly breaks apart and an ogre kidnaps the boy's mom. The boy suddenly finds himself in a fantastical and chaotic world where he does battle with a giant red ogre, gets saved by a dog (the titular Wanwa), drives a rocket car, and runs up a tree.
The boy encounters Wanwa and believes that he is asleep, only to realize that he is dead. As the boy cries over the dog, more ogres arrive to attack the boy, but the positive vibes of his mother defeats the ogres. The whole adventure is revealed to be a dream, as the boy awakens to the vagitus of his newborn sibling and his father cries tears of joy.