To Whom It May Concern, I'm Just Fine on My Own

Tomoko is 37 years old and works in the general affairs department. In the same department is a woman known for her eccentricity, Haru Hatsuse. She doesn't care at all about how others see her, wearing flashy clothes and saying whatever she feels like without reading the room. Tomoko's friends mock Hatsuse and call her "a quirky and strong willed elderly single woman." One day, Tomoko's friends start to see Tomoko in the same way and make fun of her... Do all women have to worry about having an "aging look"? Or aim for marriage? Hatsuse, who has always lived being true to herself, somehow makes other women's lives burdened with various problems, a little easier to live!

(Source: MangaPlaza)