Overall Rena's personality is quiet, dark and cynical. She tends to behave relatively normal in front of other people, usually with a neutral, negative, or depressing tone, and is never cheery or delightful - in stark contrast to Yuno.
Her relation with Yukiteru is initially twisted: she obsesses over intercourse with Yukiteru without Yuno knowing, actually stating the obvious that her cheating is wrong and still intends to continue it on and on. She states explicitly to Yukiteru that she only desires to do it with him, and no-one else. She seems to be jealous of Yukiteru and Yuno's relation since they have spent their lives together, while she was raised alone. This is the cause of the strained love triangle.
Nevertheless, after upsetting Yuno at the theme park, there is a time when she goes swimming and rethinks her actions, with deep regret, even with thoughts of not minding to drown. This suggests she also has a self-defeating personality like Yukiteru.
She calls Yukiteru by his surname, but everyone else by their first name.
She vehemently dislikes Kaori, considering her an "awful" girl, but at times can cooperate and listen with her.
Eventually, during the transitional period when Yukiteru departs from Yuno and starts living with Rena, and her childish crush becomes more like adult affection, she becomes much more caring and thoughtful - supporting Yukituru whenever he needs to.
Hobbies and interestsEdit
She enjoys swimming very much - so much that she says her death would preferably be through drowning. She is known to have beaten Yuno in a race before, suggesting she has some talent for athletics, but has little interest in ground-based sports, preferring to swim in water instead.
Rena is a slim girl of average-height with very long, straight, violet hair running down her back, with long bangs framing her face. She has dark eyes. Initially she frequently displays a cross, agitated face, neutral, or a sly smile, in contrast to Yuno's beaming cheery smiles, though much later in the series she is more relaxed and happier.
She has no siblings, since her parents split, remarried, and had their own children, leaving Rena on her own. Her father is vaguely and briefly shown in one of Rena's flashbacks. Rena states she has an "electra complex", namely she is attracted to men that remind of her of her father.
After Yukiteru's death, her baby is shown, and Rena is a single mother.