Under the clear, cold sky. When the village chief gave the signal to start, the ninja silently scattered into the mountains of the village all at once. Today, the training exercise of Hidden Demon, born from the chief's whim, begins again.

No one knows what will happen during the Hidden Demon training. That's because anyone caught by a demon is given one command. No one knows what that command will be, but the rules dictate it must be obeyed. In any case, they must escape. It seems Yoichi is one of the demons this time. The participants were a mix: some visibly nervous, some brimming with enthusiasm, and some already resigned.