
While Rena meets him and found him agreeable, she does not understand her mother's relationship with him until her mother asks her to come away with her to start a new family when she reveals that she is pregnant with the man's child. While she was born in Hinamizawa, her family soon moved away to Ibaraki for the sake of her mother's advancing career, and she used her given first name "Reina (礼奈)." Her mother starts an affair with a co-worker. Keiichi discovers this in an infamous scene in the Sound Novels, manga, and anime where she suddenly screams "Lie (嘘だ・うそだ・ usoda)!" In the trash heap, Rena has a secret base consisting of an old van she has filled with things she likes to which she retreats when distressed. Nevertheless, according to Mion, while Rena might seem cute herself, people should be careful not to anger her as she can become quite scary. Such things include the "Kenta-kun" doll, Furude Rika, Hanyū, Satoko, and any of the club members in cute punishment game outfits. She spends much of her time "treasure hunting" at the town's trash heap in search of cute things which often appeal only to her. 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. Rena has an obsession with all things cute. Her birthday falls in July, and since nearly all of the arcs take place before July 1983, Rena has not yet turned 14. Rena attends the same grade as Keiichi, but she is a few months younger than him.

