メタモルフォーゼの縁側 (Series) favorite_border

Ichinoi, a seventy-five-year-old woman living a peaceful life, unwittingly buys a boys’ love manga one day, and is fascinated by what she finds inside. When she returns to the bookstore to buy the next volume, the high school girl working there—Urara, a seasoned BL fan—notices a budding fangirl when she sees one. When Urara offers to help Ichinoi explore this whole new world of fiction, the two dive into the BL fandom together, and form an unlikely friendship along the way.

(Source: Amazon)