Rena attends the same grade as Keiichi, but she is a few months younger than him. Her birthday falls in July, and since nearly all of the arcs take place before July 1983, Rena has not yet turned 14.

Rena has an obsession with all things cute. In what the others call her "Cute Mode" (かぁいい・Kāii), she often tries to take such things home in her Take Home (お持ち帰り・omochikaeri) Mode even if they do not belong to her. Such things include the "Kenta-kun" doll