Frostians, a race of creatures who lived on the planet Chille, can teleport through space and time, and had an average life span of 200 yrs.
A Frostian cross-breeder, Dr. Burk, planned to breed the universes most powerful creature to take over Chille. Dr. Burk was lured to Earth by a powerful force Where the Kai's fought Buu, Dr.Burk saw this "Buu" had amazing strength; Dr. Burk was surprised from the power that came from Buu. Burk was almost satisfied with its power, when he was lured into the future. Present day Earth had a more powerful Buu than in the past. Dr. Burk stole a sample of Buu's skin. Afterwards, Burk impregnated 3 life forms (that he had captured) with Buu's DNA cells. One of the three test subjects where human. When the Human/Buu was born, his appearance was completely human male. Burk called the creature a Acein.
The "Buu" Shuyin (the Acein) came from couldn't age, Buu's body was suspended in time, and therefore he couldn't age. But there was a problem, Shuyin was ageing, but he was ageing really slowly, 50 times slower than an average human. By the time Shuyin was 100 years old, his body had the appearance of a 2 yr. old. When he was 5 yrs. old, Burk had already died, and his son, Myles, had taken over. Burk had spent so much time on Shuyin, which all his other tests died. Burk had taught Shuyin movement, Myles started training Shuyin. Myles found out that Shuyin already had the amazing fighting ability as his ancestor; Shuyin also had Buu's abilities. He could heal himself when he was cut or sliced, he could manipulate his body and change figure. The only difference was that Shuyin would die of old age at 5,000, But Buu's body was suspended in time; so Buu could not die of old age...
At age 8 (400) Myles' niece, Frost, had taken over, but she wasn't trying to rule her home planet. She had taught the boy language for 50 years, when Shuyin was 9, he was speaking fluent English, Frostian, Japanese, and Namekian. When Frost was 190, her dying words told the story of how he was created, and what he was created for. Frost then used the last of her power to freeze Shuyin; this was for the protection of Chille. He would still age, this was part of her plan, to keep him frozen for 4,500 years, by then he would have died of old age, this would prevent him from destroying Chille. Hopefully he wouldn't be unfrozen until he died.
400 years later, Shuyin was unfrozen by a huge explosion in the lab, Frost's grandson, Téles, had created (and died in) the explosion by accident. Shuyin was 17 (850), he just started to recollect what had happened. He remembered Burk teaching him movement, and Myles teaching him defense, and Frost teaching language, and then he remembered what Frost had told him. He was created from Buu and created to destroy Chille, and then he remembered being frozen. In anger, Shuyin collected Téles latent energy to create a portal to Earth. Afterwards he rarely spoke; sometimes it was between years when he spoke.
It ends up that the fact that Frost had sealed Shuyin inside of the ice mixed with the explosion has messed with his left arm and he was no longer fully capable of using his left arm, so Shuyin had to get his arm surgically removed. Shuyin soon got use to Earths gravity and even trained himself to become an even fiercer fighter despite his disability.