Penguin Highway (manga)

One day, penguins are spotted in the suburban town that fourth-grader Aoyama calls home. The penguins make their sudden appearance in a residential district—nowhere near the ocean—and disappear just as mysteriously. Where could they have come from, and where did they go? Aoyama is determined to get to the bottom of it! This is the slightly curious, unforgettable tale of that summer.