Oba-chan is a supporting character in the anime Astro Note. She is an older woman, described in official material as a refined madam, who lives in the Gotokuji area where the series takes place. She is connected to the neighborhood around the Astro-sou boarding house and sometimes appears in the local shopping district, where running into her is treated as an event that can easily turn into a long exchange.

Her most defining trait is her love of conversation. She is very knowledgeable about local affairs and enjoys discussing and spreading gossip, keeping an ear open for rumors and information about the people around her. She is known for talking at length once someone is caught in conversation with her, and she has a taste for somewhat flashy clothing.

In the story, she serves as a well-informed neighborhood figure whose gossip keeps her close to the lives of the residents of Astro-sou. Her position in the narrative is played for ambiguity: the series teases whether she will support the chef Takumi in his feelings for the landlady Mira or instead become a meddlesome nuisance in their relationship.

Her key relationships are with the residents of the boarding house, particularly Takumi and Mira, as her knowledge of neighborhood news places her at the edges of their daily lives and the unusual events that unfold around them. Her personal background is not a focus of the series, which presents her primarily as a talkative, familiar local personality rather than a figure in the main mystery.

Her notable abilities are not combat-oriented or supernatural. Instead, her strength lies in information gathering. She is highly attuned to rumors and local news, making her exceptionally well informed about the area, and she willingly shares what she knows with others, whether or not they want to hear it.