Since childhood, Kazuhiro Kitase has been able to dream of a different world. He can return to reality by falling asleep or dying, and he can pick up where he left off by sleeping again. For years, he has had many adventures alongside Mariabelle, a beautiful elf who works for the Sorcery Guild.
On one of their escapades, they come across the lair of a dragon taking care of its eggs. They inadvertently wake the slumbering beast, who promptly reduces them to ashes. For Kazuhiro, it is merely a temporary setback, as he can simply go back. However, he is shocked to find Mariabelle herself safe and sound asleep next to him. Kazuhiro realizes that his dream world is an alternate reality altogether. In the meantime, he makes the most of this bizarre circumstance, introducing Mariabelle to the sights and wonders of Japan. Now, with their time together spanning two worlds, their real adventures have just begun!