Dragon Ball Z. Volume 4

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.
With the mighty Kaio-ken amplifying his strength, Goku fights Vegeta in a desperate battle to save the world--only to find that the elite Saiyan warrior is even stronger than his new techniques! In desperation, Goku calls upon the Genki-dama, the "spirit ball," drawing power from the Earth, its people, plants, and animals. But alone, even Goku is not enough. The last worn-out survivors, Gohan, Kuririn, and Yajirobe, must rush back into the fray to beat the unbeatable Vegeta...as their enraged foe vows to not only wipe out the human race, but destroy the planet Earth itself!