Tapion comes from a planet very far away from earth and from 10,000 years in the past. Tapion arrives on Earth in a music box that Gohan and Goku can,t even muscle open. The Dragon is called and the Z Fighters make a wish for the Great Hero Tapion to be freed from his prison.
After Realeasing Tapion the Z Fighters realize the reason why Tapion was imprisoned and the danger the earth now faces. 10,000 years before and ancient and evil race bend on universal control revived the ancient and evil creature Hirudegarn from a location on Tapion's home world. Hirudigarn had been defeated ounce along time ago by Tapions ancestors .
Tapion and his brother took it upon themselves to go to the location were Hirudigarn had been revived and in doing so they found two Ocarinas and a magical sword (the Z Sword). Tapion and his brother brought these items back to help fight Hirudigarn. As an old wizard wielded the sword against Hirudigarn Tapion and his brother played the Ocarinas, driving the beast into a rage but also becoming immune to his attacks. While the beast was distracted the old wizard took up the sword and sliced Hirudigarn in two.
Hirudigarn was then imprisoned into Tapion and his brother, the top half into Tapion and the lower inside of his brother. The brothers were then to be sealed into music boxes until a later time inwhich they could be released and Hirudigarn defeated once more.
When Realeasing Tapion from the music box they also released Hirudigarns Upper Half.
After begoming close friends with Kid Trunks tapion finds out that his brother has also been released and killed by Hirudigarns lower half. Faced with the power of Hirudigarns lower half Tapion can no longer hold the beast within and Hirudigarn is released and whole once more.
After a trying battle Hirudigarn is defeated by Goku and Tapion Leaves Earth, after giving the young Trunks his sword.
All of this Takes place in the 13th DBZ movie THE WRATH OF THE DRAGON