It has been ten years since Buu was defeated. Goku, Goten, Vegeta and Trunks enter the World Martial Arts Tournament, where they also meet up with old friends and family.

Soon after, Gohan saves the passengers of a plane about to crash and extinguished a fire that caught fire in a building in the city by destroying the water container. On his way to school, Gohan is chased by Videl in her helicopter, who is trying to find out who is hiding under the mask of Great Saiyaman. Gohan escapes by placing Videl's helicopter on the roof of a building. Both of them arrive to school late, which leads Videl to be even more suspicious of Gohan. Later, kidnappers from the Red Shark gang take the mayor of Satan City hostage. The police warn Videl of the situation, so she responds by confronting the leader of the gang. Meanwhile, Gohan, growing impatient of class since he would rather assist Videl as The Great Saiyaman, starts aggressively tapping his foot, triggering an earthquake. He slid out of class during the confusion and arrives to the scene of the crime as the Great Saiyaman. Gohan saves the mayor of the city while stopping the attempts of the rest of the gang. Videl learns that Gohan was out of school at the same time. Videl is led to believe that Gohan and Great Saiyaman could really be the same person.