I'm a librarian who loves anime, manga, and reading a wide variety of genres.
There are direct mentions of homosexuality and asexuality after Keiko inadvertently admits to the few friends she has outside of work that, although she's 36, she's never dated anyone. The thing that bugs Keiko (sort of, since I'm not sure anything really bugs her) is that everyone is assuming she's miserable in her husband-less, date-less, child-less state.
The one person in Keiko's life that she seems to be completely honest with is her sister, who gives Keiko advice on what to say in certain situations in order to seem more like everyone else. I'm hoping her sister gets some on-page scenes.