Senka Yorozu is the landlord and owner of the Yorozuyo Inn, providing residence and guardianship for Kazuma Hoshino and his younger brother Ayumu during their stay in Yamabiko, as a longtime family friend of their father.

She has a mature, slim build and pale skin, with straight, long black hair reaching her hips and blunt bangs, often styled in a bun secured by a kanzashi hairpin on the right side. Her eyes are blue. She typically wears a yukata or kimono, though she is also seen in jeans, a tank top, a nurse uniform, and garter belt stockings.

Friendly, hospitable, and motherly, she is also hard-working and strict, particularly in demanding proper behavior from guests, with a frank, no-nonsense attitude and little tolerance for rudeness. She enjoys drinking sake and often engages in flirting and teasing, displaying a mischievous side, especially toward Kazuma. She dislikes being called "Oba-san" and prefers "Nee-san."

She grew up in Yamabiko and attended the same local school as Kazuma and his friends. In her youth, she assisted her father in managing the inn and was described as quiet and obedient. After graduating high school with excellent grades, she left for university in the city. During her later university years, her father was diagnosed with a terminal illness and passed away shortly after. Feeling guilt over not being present in his final years, she dropped out and returned to Yamabiko to take over the inn.

She holds a familial, guardian-like role toward Kazuma and Ayumu. In the fandisc narrative, after living together for over a year and working part-time at the inn, Kazuma develops romantic feelings for her and confesses. She initially dismisses this due to their ten-year age gap but later reciprocates. However, she ends the relationship weeks later, fearing she is hindering his university prospects and future. After Kazuma reaffirms his commitment and choice to stay and work at the inn, they reconcile. She maintains a friendly relationship with Tsumugi Toudou, a part-time employee she addresses as "landlady," who becomes a full-time employee after high school.

In the original visual novel and anime, she is a minor character, but she is one of the three main heroines in the fandisc "Hoshizora e Kakaru Hashi AA," where her backstory and romantic route are expanded.

Her surname Yorozu means "ten thousand," and her given name Senka means "thousand" and "song."