There's a rumor that children in the city are disappearing one after another. Upon hearing this, Mana contacts Kitarō in order to elucidate the truth. However, Kitarō bluntly states that "Yōkai and humans can't be friends." It turns out that children were kidnapped in order to resurrect the Yōkai Castle that was once sealed. This time, Mana was kidnapped as well. Kitarō's friends join him in the effort to rescue the human that saved his life!