圭一の同級生。
献身的な性格で、毎朝一緒に学校に通うなど、圭一とは一番の仲良しである。「かぁいい」ものに目がなく、見つけると手当たり次第自宅に「お持ち帰り」してしまう癖がある。
「かぁいい」モードに入ったレナには一切の物理法則が通用せず、手に負えない。
Keiichi's classmate. She has a caring personality and is Keiichi's best friend, always walking to school with him every morning. She loves anything that's "kyute,"and has a bad habit of trying to take "kyute" things home with her. When she goes into "kyute" mode, she goes out of control and all physical laws cease to apply to her.