Teruki Maeno's only daughter and Kōki's granddaughter, first appearing as a teenager in episode five. Finding Teruki's old video of Rin, she starts investigating her, frequently comparing herself to Sherlock Holmes. Upon the first meeting, they quickly grow fond of each other, and Mishio has been hanging out with Rin and Mimi since then. In episode six, Rin explains that Mishio is the youngest of Tajimamori's descendants.
From Wikipedia.