Lost in the forest on his way home, Takashi Natsume is saved by a youkai couple who craft magical sake cups. Drinking from the 'One Night Cup' fills him with energy, but its effects fade by morning. Joined by his guardian Madara, a sake-loving chubby cat, Natsume attends a youkai banquet and learns the art of making sake cups. Later, Natsume regrets declining a banquet invitation from Madara and follows him to a mysterious mansion where a game involving youkai unfolds. Guided by the alluring youkai Hinoe, Natsume discovers the mansion's role in a supernatural contest for dominance over a valley, leading him to unsettling dreams of becoming a player in this eerie game.