Starborn

As The Great Shatter wipes out most of the human race on Earth, the STARS are in a hurry to restore it. A young starborn, Yuusei, offers his help and aid in the mission, offering to go down to Earth, get the all-powerful glade, a swod of his "grandfathers" that containes immense power, and bring back the life to the world.

Turn out, its been 230 years since his departure, and to rassure his safety, two other starborns are sent down after him. They quickly realize that their beloved friend still exists, just not the way they knew him, even having a different name.