Masao-Kun is a regular supporting character in the sixteenth Crayon Shin-chan film, appearing as one of Shinnosuke Nohara’s classmates in the sunflower class at Kasukabe Kindergarten. In this movie, his background remains consistent with the series: he is a five-year-old boy who is timid, sensitive, and easily frightened. His personality is defined by a gentle, somewhat nervous disposition, and he often looks to stronger friends for reassurance. In the story, Masao-Kun’s role is minimal compared to the main adventure. The film’s plot revolves around Shin-chan being chosen as the hero of the golden spear to fight the dark world ruler Don Kurai, and the focus shifts heavily to the new characters Mata Tami and the transformed dog Kuro. As a result, Masao-Kun’s presence is notably reduced; he appears mostly in group scenes with the other kindergarten friends but does not drive the action. His key relationships remain with Shin-chan, Kazama-kun, Nene-chan, and Bo-chan, though these bonds are not explored further in this entry. Masao-Kun exhibits no special abilities or notable development. The dark world’s influence causes minor disruptions to everyday life, but his character does not undergo any change or personal growth. He simply accompanies the group as a background observer, underscoring his typical role as a quiet, ordinary member of the Kasukabe Defence Force.