Height: 155cm
Age 16 (Hidamari Sketch-365) 17 (Hoshimittsu-Honeycomb)

Hiro is a year older than Yuno and Miyako, living directly under Yuno's apartment. Although she tries to be a supportive senpai to the girls, she tends to worry excessively about her weight, causing her to go on diets for periods while occasionally binging on sweets. She met Sae in the first year of High School, and is one of her neighbor's principal sources of support when she's involved with a deadline or other crisis.