With their new companion Sadamitsu, Raiko and Tsuna approach the caves where the Tsuchigumos dwell. Inside the caves they meet with Kuzume, a young girl from the village kept in captivity by the Tsuchigumo clan. Raiko and her team advance deeper and deeper inside the cave, and in the innermost recess of this underground world, they finally see an altar emanating a holy light: it's the Magatama! But a huge shadow steps before them: for Raiko and her friends, it is time to face Hoshikuma, the feared commander of the Tsuchigumo clan!