Yōko Miyakoshi is the 36-year-old mother of Hana Miyakoshi and works as a chef for a local television program. She stands 165 cm tall with long dark tan hair and brown eyes. Her relationship with her daughter includes moments of concern and confusion, notably when Hana returned home visibly upset after staying overnight at Daisuke Higashida's residence. Despite Yōko's questioning, Hana offered no explanation, leaving her mother perplexed.

The surname Miyakoshi, shared with her daughter, combines the characters for "temple, shrine, palace" (宮) and "exceed, climb, surpass" (越). Her given name Yōko derives from the characters for "leaf, plane, lobe" (葉) and "child" (子).