Near the beginning of human history, there was a mage called House. Though the manipulation of ki with magic, he achieved a power level near SSJ3. One day, he killed his son Flat by accident. Filled with sorrow, he decided to punish himself for eternity. So with his power, he created a different dimension with extremely harsh environment and stayed in there. The entrance to the dimension was guarded by his best friend Dome. Dome was the first Kami of the world and the dimension is now known as RoSaT.
Generations later, this story was long forgotten and many Kami used RoSaT to trap foes they could not handle. The most powerful of them all was a tyrant called Cave with a power level near SSJ2. Again, generations had passed and the story of Cave was also long forgotten and RoSaT was used for training by the last few generation of Kami. Well, they were long forgotten until Vegeta and Trunk went in for a year.
Over the years, House¡¦s body had merged with RoSaT and since existed as spirit form, but still felt the pain he imposed on himself. On the other hand Cave defeated all others in RoSaT and absorbed their power. He split up into 8 parts sealed himself into a long sleep to escape from the pain of living in this harsh dimension, waiting for the day of revenge.
Sensing the power of USSJ Vegeta, Cave slowly emerged from his sleep. By the time all parts were free, Vegeta and Trunk were replaced by Goku and Gohan. Filled with anger against Kami, the parts attacked them. Goku and Gohan were shocked to see other beings in RoSaT and fought back. The parts were as strong as Freeza and were soon defeated. Then they combined together to form two stronger beings. The battle was very intense and within four hours, they exchanged over fifty thousand ki attacks. Finally the combined Kamehameha of SSJ Goku and SSJ Gohan forced the parts to combine back into the original form - Cave.
Goku and Gohan could not keep up with Cave and Goku took a few critical hits while shielding Gohan from harm. House was watching the fight all this time but when he saw how Goku helped his son, he remembered about his own son and decided to help them. He told Goku that he would give Goku his energy and Goku should start charging a ki attack. Goku started charging a spirit bomb because this was the best method to handle external energy source. Gohan saw this and charged up into USSJ to hold off Cave. The whole dimension started to shake as House had trouble sustaining the dimension while giving energy to Goku and holding Cave from breaking out of this dimension. Gohan held Cave from the back while Goku fired from the front. At the critical moment, Goku IT next to Gohan and IT both of them away from the explosion.
House told Goku and Gohan about his story and Goku wanted to help with the dragonballs. House refused, saying he son should have many friends in the afterlife by now. Goku said it was possible for Flat to return and stay with House for a day, a year in RoSaT, but he had to wait until after the Cell game. House said he didn¡¦t mind waiting because he waited this long already. Goku and Gohan spent the next nine months with House while training for the Cell game. In an unknown corner in RoSaT, House made a beautiful garden, waiting for his son to visit him.
The End