In a quiet corner of the city, four-year-old Kun Oota has lived a spoiled life as an only child with his parents and the family dog, Yukko. But when his new baby sister Mirai is brought home, his simple life is thrown upside-down; suddenly, it isn't all about him anymore. Despite his tantrums and nagging, Mirai is seemingly now the subject of all his parents' love. To help him adapt to this drastic change, Kun is taken on an extraordinary journey through time, meeting his family's past, present, and future selves, as he learns not only what it means to be a part of a family, but also what it means to be an older brother.

Watch the trailer

The film was nominated for Best Animated Feature Film at the 76th Golden Globe Awards, Best Animated Feature at the 24th Critics' Choice Awards and Best Animated Feature at the 91st Academy Awards. It is the sixth anime film, and the first non-Ghibli anime film, to receive an Academy Award nomination in the category. The film also won Best Animated Feature — Independent at the 46th Annie Awards.