Nana the cat is on a road trip. He is not sure where he's going or why, but it means that he gets to sit in the front seat of a silver van with his beloved owner, Satoru. Side by side, they cruise around Japan through the changing seasons, visiting Satoru's old friends. He meets Yoshimine, the brusque and unsentimental farmer for whom cats are just ratters; Sugi and Chikako, the warm-hearted couple who run a pet-friendly B&B; and Kosuke, the mournful husband whose cat-loving wife has just left him. There's even a very special dog who forces Nana to reassess his disdain for the canine species.

But what is the purpose of this road trip? And why is everyone so interested in Nana? Nana does not know and Satoru won't say. But when Nana finally works it out, his small heart will break...