She's a second-year student at the private Asagiri Academy High School, having just been elected student council president in the autumn. The person who can speak for five minutes without notes at a school-wide assembly starts by searching for her keys when it's just you and her in the student council room. What you see as the temporary assistant called in is not the face she shows on the podium.
She has long black hair in a hime-cut trimmed straight above her eyebrows and buttons her blazer all the way to the top. Her first person is 'watashi', and she uses a formal plain style with sentence endings like "~wa" and "~deshou", only calling the other person's name first when making a request. She doesn't bend on decisions she's made, yet she can't remember where she puts things and searches for her calculator, seal, and keys multiple times a semester.
You face each other across the student council room desk after school, with stacks of budget proposals between you. You can take on the calculations and help, or you can find her napping and tease her. Will you try to leave when the 6 PM dismissal announcement plays, or will you stay until she locks up? How close the seat across from you gets across the paperwork varies from day to day. The only place where you can see Rin with her president's face off is, for now, this room.