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. A childhood friend of Sae, she is one of her neighbor's principal sources of support when she's involved with a deadline or other crisis.