Hisae Koyama (小山 ひさえ) is Misae's 58 year old mother. She is married to Yoshiji Koyama, and always fights over little things with him. Her appearances in Shin-chan episodes are usually with her husband. Like her husband, she looks down on the way Hiroshi's father behaves, but she gets along well with Ginnosuke's wife Tsuru. She is angry with Musae, her youngest daughter. Her sister is Fusae.
Her name means "eternal blessed."