Naoki Kazumi lost his parents in an accident and, with nowhere else to go, now lives with his cousin Matsuri Shibugaki. One day on the school rooftop, a girl drops out of the sky. She is Mikoto Amagasaki, a traveler from a century in the future who came back in time hoping to track down her missing brother. When she sees Naoki, she takes him for that brother. This four-episode OVA follows the Mikoto storyline and mixes comedy, drama, romance and science fiction.