Miko Shibuya, also known as Jennifer Shibuya, is the wife of Shouma Shibuya and mother of Yuri and Shouri Shibuya. Born and raised in Tokyo, Japan, she is fully human with no demonic heritage. She attended Ferris University in Yokohama, where she joined the fencing club and competed in the Universiade. It was there she met Shouma, marrying him after only five meetings despite knowing he was a Mazoku—a demon—and that her sons were destined to become Demon Kings.

Her personality is consistently upbeat and cheerful. She speaks at a very fast pace and accepts surprising news with remarkable ease, such as her son Yuri's engagement to the demon Wolfram von Bielefeld. A devoted wife and mother, she actively involves herself in her sons' lives, offering advice and care.

She possesses a strong interest in fantasy, which fuels her active imagination. Upon learning her husband was a Mazoku, she expected physical demonic traits like wings, a tail, or horns, and was similarly disappointed when her sons were born without such features. This led her to dress Yuri in girls' clothing during his childhood, partly due to her wish for a daughter.

She prefers the name "Jennifer," adopted after a computer fortune-telling program suggestion, which earned her the university nickname "Hama no Jennifer." Her sons typically do not call her "Mom" or "Mommy."

She manages household duties like cooking and cleaning, serving as a supportive figure for her family, though her nurturing can sometimes be overbearing. A doppelgänger of Miko appeared briefly in an episode, but it was a trap that expanded and exploded shortly after appearing.