The Ryuguu Turtle is Discovery number 77.
Once upon a time, an old man rescued a turtle who was being picked on by the neighborhood children. Thanking the old man, the turtle offered to give the old man a ride on his back. So, into the sky they flew, to a far away land.-A Yafutoman Legend.
The turtle heads south west traveling underneath Tenkou Island while in central sky. Then when the dark rift comes in sight it makes a sharp turn and heads South East at which point it begins to ascend into Upper Sky. Once in Upper Sky it continues to ascend while it turns gradually towards the North East. At it's highest point it will turn and begin descending. At this exact point it passes over Ryuugu Island.