Mirai no Mirai (2018)

A young boy of four-years-old (Kun) is awaiting the arrival of a new baby to the family. These Japanese parents are young, and Kun is their only child. The boy ends up having a mystical and adventurous experience with a magical garden. This majestic garden allows Kun to travel where the laws of standard physics don't apply. The boy travels through time where he interacts with relatives from many different eras. Kun also receives important guidance from his yet-to-be-born sister that is from the future, during his time travels. Kun also witnesses his dog morph into an adult man at one point.