Toki's older sister (however she has no memory of him), in second grade and vice-president of the student council. Like her brother she has heterochromia but hides it by wearing glasses. She has a strange habit of grabbing Sakura's breasts out of nowhere (something her brother tries to do to Sakura as well), cuddling herself against them and falling asleep on them; going so far as to name them (Mii-tan for the right and Hii-tan for the left). Her behavior is childish most of the time.
Nenene is, in fact, an Ex-Code:Breaker. In a battle with Re:Code 03 Kouji, she died protecting Toki. The reason she still lives in the present, her lack of memories regarding her past as a Code:Breaker and how she turned into a child is currently unknown.
After the Code:Breakers' battle in Shibuya mansion with "The Seeking One", Nenene apparently regained her memories, and was even able to chat with Toki and Heike. According to her, it was due to the Pandora box being opened again. In this state, she's shown to have a more forceful personality.However, she soon passed out afterwards, and again woke up without memories of her past self.
In the past, Nenene was the Code:04. She was infamous among the Code:Breakers and Re:Codes for being a cold-blooded killer, always single-mindedly dedicated to her missions, all the while sporting a gentle smile. She was also one of the anti-rare kind Jokers.