Dragon Ball Z, Vol. 20 : The New Generation Volume 20 by Akira Toriyama

Sci-Fi martial arts action!After years of training and adventure, Goku has become Earth's ultimate warrior. And his son, Gohan, shows even greater promise. But the stakes are increasing as even deadlier enemies threaten the planet.

DRAGON BALL Z is the ultimate science fiction-martial arts manga. Dragon Ball Z fast-forwards into the future! Years after the battle with Cell, the Earth has forgotten about the existence of the super warriors, and Gohan is living the life of a mild- mannered high school student. Mild-mannered until evil strikes,that is...and the world needs the power of the Great Saiyaman!As Gohan's high school classmates ponder the similarity between their classmate and the masked crimefighter, two even stronger warriors prepare to make their names known.

Their names are Goten and Trunks, and though they're not even out of elementary school, they may be the toughest things on the planet.