Mineko Seki is grandmother to Oriko "Okko" Seki and proprietor of the Harunoya Inn, a traditional hot springs ryokan in Hananoyu. Her gray hair features a distinctive purple stripe. Following the tragic car accident that claimed Okko's parents, Mineko becomes her guardian, welcoming her to live at the inn. Mineko embodies kindness and deep consideration, showing profound mindfulness of others' feelings, especially Okko's grief. Initially hesitant to involve Okko in inn responsibilities due to her recent trauma, Mineko is overjoyed upon overhearing Okko express a desire to become an innkeeper. She promptly appoints Okko as junior innkeeper, supporting her in this role with the assistance of staff members Etsuko and Kōnosuke Minoda. Mineko connects Okko to her family history by showing her the room once belonging to Okko's mother. Her practical care includes providing dry clothes when Okko falls into a pond. Mineko shares a childhood friendship with the ghost Makoto "Uribo" Tachiuri, who remains at the inn. She manages Harunoya guided by a philosophy of hospitality, declaring the inn "rejects no one." Throughout Okko's adjustment and training, Mineko provides a stable, nurturing environment, facilitating her granddaughter's gradual healing and growth into the role of innkeeper.