Mineko Seki is the elderly proprietor of Hananoyu Inn, a traditional hot springs ryokan in the town of Hananoyu. She possesses gray hair featuring a distinctive light purple stripe. After the death of Oriko Seki's parents in a car accident, Mineko became her granddaughter's guardian, welcoming Oriko to live at the inn and showing her the room once belonging to Oriko's mother, Mineko's daughter.

Kind and considerate of others' feelings, Mineko hoped Oriko would eventually take over as innkeeper. She hesitated to raise the topic due to Oriko's recent trauma and grief. Mineko felt profound relief and joy upon accidentally overhearing Oriko express a desire to run the inn herself, resolving Mineko's internal conflict. She then openly supported Oriko's training as a junior innkeeper, involving her staff.

Mineko spent her childhood in Hananoyu, where she was friends with Makoto "Uribo" Tachiuri, her next-door neighbor. Uribo died young, and his ghost later became a presence at Hananoyu Inn. Mineko continues to manage the inn's operations with her staff, upholding its traditions, hospitality, and core philosophy of accepting all guests without rejection.

Her role remains consistent as a supportive figure guiding Oriko's growth as an innkeeper while managing the ryokan. Mineko's development focuses on navigating her granddaughter's grief and nurturing Oriko's newfound dedication to the inn. Across all adaptations, Mineko serves as a stabilizing influence, embodying the inn's values of service and compassion without undergoing significant personal change.