Shuntarou Harumi is one of Punpun's childhood friends. He initially plays a minor role and is absent for most of the manga, but returns in the final chapters to play a pivotal role in the story's conclusion.
Harumi has medium, messy hair in elementary school and as an adult. He is usually seen with a smile on his face in most of his appearances. He wears casual clothing such as T-shirts in elementary school and formal attire while teaching as an adult.
Harumi is a kindhearted, considerate, and caring person. He frequently shows concern for others such as his girlfriend and Mama Punpun.