A mysterious giant capsule suddenly appears in a forgotten onsen (hot spring) town! Although, the mayor is taking pictures and looks oddly happy? Mons-Ahgar appears to throw GUTS-Select and the town further into chaos! Their hopes to save the day lie in promising new technology, and so Kanata and crew turn their efforts into combining the two GUTS aircrafts into one: the GUTS Gryphon!

The Sasamedake flower blooms. It is said to be the harbinger of disaster! Then, a golden rainbow appears in the sky! As if responding to its call, a subterranean monster appears! Ryumon is injured as this unprecedented situation unfolds. Kanata tries to cheer him up, but....what lies at the end of Ryumon's gaze?