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Aizawa Ayumu is a young boy, who is sent to a small town called Tana to live with his father for a while. Even though he doesn't want to go, he agrees to do so when his mother offers him a mountain bike. Ayumu used to live in Tana before, and now his memories of the time are shrouded in mystery - apparently something happened when he was a child. Enter Miku, a young girl who knows more than she tells, weird glowing lights floating around, reflections of UFOish objects in the eyes of cats and dogs, a nosy female announcer, a forest with a mysterious past, and a weird boy called Wakkun, who wears the clothes Ayumu used to when he was a child, and you get the world of Zettai Shonen, where mysteries remain mysteries amidst a slow, normal, everyday life.

Source: Wikipedia