Riku Harada is the elder of the Harada twins. Unlike her younger sister Risa, who prefers fashion and obsessing over relationships,
Riku is more into athletics (lacrosse being her sport) and academics and can be considered to be somewhat of a tomboy. She
acts "less girly" compared to her sister Risa and is more serious, independent and down-to-earth. In terms of physical features,
her hair is much shorter (about shoulder length) than her sister's and she displays more stamina and fitness (Risa is chauffeured
to the train station then rides Riku's bike to school compared to Riku riding her bike to meet her sister than jogging the
rest of the way).
She holds an intense dislike for Dark Mousy ever since their first encounter in which he had spotted her after she was done taking a shower then stealing her first kiss.
In the anime, he landed on her balcony as she stood outside. Upon seeing him she was startled and in his attempts to quiet
her down as to not attract attention, he kissed her. The fact that he stole her first kiss added to her extreme dislike of
Riku was not always as close to Daisuke as her sister was to him, she was only thought of by Daisuke as just Risa's
older sister. She did, however, harbor some feelings for him to which she never admitted to anyone, even to herself (this
can be seen in some subtle changes in her actions whenever the topic of Daisuke and Risa pops up). Before then, she considered
Daisuke as being clumsy, unreliable and not having any apparent qualities that would be of interest to her. Although, as their
relationship grew closer she becomes more aware of his strengths and personality and her true feelings start to emerge. Also,
rekindled memories from her childhood in which Daisuke (though not knowing who he was at the time) had done very kind things
for her contributed to her developing feelings for him. She even showed certain amounts of jealously to Mio (in the anime)
and even towards her surname (in which Daisuke calls both of the twins by their surname, "Harada-san", subconsciously she
wanted Daisuke to call her by her name) Later on, she finally admits her feelings to Daisuke, and at the same time he admits
his feelings for her as well, and they start going out.
Daisuke's alter ego, Dark, appears show some attraction to her. Riku, on the other hand, does not show the same towards
Dark often regarding him as a pervert (since he stole her first kiss) and openly showing her dislike for him.
She also notices that Daisuke can be relied on and is a caring person when he jumps off a ledge to save from a dangerous
fall. Also when she twists her ankle Daisuke carries her up the whole side of the mountain to reach Risa. When he shows that
he is worried about her she blushes and starts to realize her true feelings and emotions for Daisuke.Riku is the polar opposite
of her sister, Risa, preferring outdoor activities and athletics than to obsessing over crushes and clothes. Compared to her sister she is more
down to earth, articulate and athletic. She is also very assertive, serious and independent. Despite such differences both
of Risa and her do share some similar qualities such as bravery and stubbornness. However, unlike Risa, she is quite shy about
her feelings towards others, especially towards Daisuke and doesn't openly talk about her feelings, although Risa is still
able to pick up the fact the she likes Daisuke. Her cooking skills are far better than that of her sister's and in episode
5 Risa says she didn't know how popular Riku is. She is also quite kind-hearted, caring, and selfless, wanting only the best
for everyone. She is also quite protective of her sister, very concerned whenever Risa goes out to see Dark or is distressed.