Raiga and Kuga, as well as Tetsu, are attending a field trip to Orange Pit, where their grandfather works as a mechanic. (Rin stayed home, because she'd already been there many times.) Back at Earth, Bariki is quite unhappy over the choice of field trip, due to unsettled feelings between his father and him. Manriki used to be a member of Earth as well, and helped in developing the Core Granners. However, he suddenly decided to quit once development on Gao Granner Leo and Gao Granner Eagle began...