In a hot and nostalgic Japanese summer, we follow a boy named Kikujiro, who feels somewhat lonely and yearns to lose himself in a world full of adventures. His mother, very busy with her work, leaves him in the care of his grandmother, which intensifies his feeling of abandonment. However, the young boy's life takes an unexpected turn when he crosses paths with the peculiar figure of an adult man named Kikujiro, who seems to be the exact opposite of what one would expect from a caretaker.
Kikujiro is a rough and somewhat scruffy man, but he has a heart of gold and a free spirit. Together, they embark on a journey through the Japanese countryside, where their relationship transforms into an unusual friendship. As they traverse the summery landscapes, filled with laughter, games, and the occasional mischief, both learn to leave behind their respective loneliness: Kikujiro rediscovers the wonders of childhood, and Kikujiro finds comfort in the company of someone who, despite being a bit chaotic, provides the attention he longs for.
Amidst touching and surreal moments, the film evokes a blend of humor and melancholy, revealing the beauty of human connections. The relationship between the boy and his strange friend becomes a reminder of the importance of friendship and love in the most vulnerable stages of life, as they face together the warmth of summer and their own inner demons.