In ancient times, humans live alongside spirit youkai. When demon youkai decide to take control of humans, the two kinds of youkai fall into a violent conflict. A swordsman then appears and shows both sides a way to fight without killing one another. From that point, the side that wins gains great power in the human world, keeping it until the day the winners remove a seal from the losers. Now the bamboo is in full flower, which means the day to lift the seal has arrived. The victorious demon youkai hold the power and vow to win the next battle and keep humans under their control forever. This time, though, victory or defeat rests with a supreme commander who must be a human child. Nurarihyon, head of the spirit youkai, foresees this and orders Maya to search for a suitable candidate.