Penguin Highway

In Penguin Highway, Aoyama-kun is an intelligent and studious 4th grade student who is constantly jotting down everything that he learns in his notebooks. He is also on good terms with "Onee-san", a young lady who works at the dental clinic that Aoyama-kun goes to. Aoyama-kun is shocked one day when he encounters a penguin in the middle of his suburban town, which is nowhere near the sea. The mystery only deepens when Aoyama-kun observes "Onee-san" tossing away a can of cola, only for the can to turn into a penguin!

(Source: Crunchyroll)