10年に1度、地球に近づく大型すい星ドリームコメット。優は幼い頃、ドリームコメットに住む紳士Mr.ドリームの話を聞かされていた。その紳士はいろいろな星の子供たちに夢をプレゼントして回っているのだ。自分の所にも来てくれると信じる優の前にMr.ドリームが現われた。素敵なパーティーに招待され、優は楽しい時を過ごす。
Yuu recounting a conversation with her father Tetsuo about the stars in the sky and the fable associated with the decennial Dream Comet gives way to a news broadcast about the Dream Comet as Yuu finishes making a crepe for Midori that sets the stage for Yuu to prosecute a divergent concourse regarding the existence of Mr. Dream with Toshio who plans to observe the Comet that night with Midori. Later that evening while staring up at the sky, Yuu explains her childhood prologue with Toshio whose detection of the Dream Comet becomes the forum for Mr. Dream to manifest himself before the astonished Yuu as he explains the adventure ahead of her that night. Yuu's adventure with Mr. Dream begins with some elements of »Alice in Wonderland« that enable Toshio to spot Yuu well enough to give chase after her; while unable to follow Yuu to the dimensional area where the secret clubhouse is located, Toshio's anxiety for Yuu's welfare is a potent deus ex machina that ultimately adds enough element
