マミのCM撮影で、渓谷へ来たパルテノンプロ一行。渓谷にある鍾乳洞には黒い雄鹿の伝説があった。一行とは別に俊夫たちと来た優が鍾乳洞に入ると、中の石塔の下から声が聞こえ、石をどかすと黒い小さな鹿が現われた。撮影のため現場に急ぐ優に次々事故が起こる。鹿が原因だというネガをたしなめマミが鹿を慰めると・・・。
While Hayato and Shingo compare notes with Megumi about whether Creamy Mami will be punctual for an advertisement filming in a wilderness area reputed to have a black stag that has been visiting unto the locals bad luck, Yuu daydreams about being on a date with Toshio cured of his Creamy Mami addiction but causes a misunderstanding on the train when she speculates out loud Toshio and Midori's hidden motives for the outing; during the bus ride from the train station, Nega and Posi compare notes about the legend describing a magical stag that once resided on the Feather Star along with the pros and cons of emancipating the mystical ungulate from its subterranean prison. The astonished adoration of the black stag quickly gives way to it being time for Yuu to do her thing as Creamy Mami. The black stag's risky shortcut whose zenith is being trapped on a high rock ledge has the ironic silver lining of ultimately being the commercial Creamy Mami is to have done originally; now his former gol
