Plot: With Kaito's group stuck between flights, Cubic and Ana go ahead of them to Rio de Janeiro, where they meet a woman named Regina Maria Vasco. Taking them to a hidden cave under the pretense of helping them find Raetsel, Regina reveals herself to be a Master Brain and traps Cubic and Ana in a Fools' Puzzle, in which they must travel via canoe across several containers whilst making sure they end up with equal volumes