Yūki Mikan

Mikan Yuuki is Rito 's independent and reliable 12 year-old sister. Mikan takes care of the housework while their parents are away on business and watches after Celine. In contrast to her brother, she is very mature and does not hesitate to tease him, going as far as stating they aren't blood-related, but quickly retracting the statement, playing it off as a lie. Mikan also seems to have a certain lack of respect for Rito because of this (she hardly ever addresses him by his honorific as an older brother), but does answer him "Onii-chan" as thanks for trying so hard to take care of her when she develops a fever and when he gives her a Christmas present.

Mikan has grown quite attached to Golden Darkness, perhaps due to Darkness seemingly being the same age as her. Mikan is very perceptive and seems to be able to read people's emotions, even their reactions, most of which is Rito's obvious anxiety around Haruna Sairenji and Yui Kotegawa's subtle feelings for him. Mikan even calls him a "playboy" (so does Nana) for attracting so many girls all of a sudden (even though she attracts so many boys at her school). Mikan, however, does respect Rito's relationship with Lala, even going so far as to tell Momo not to get too close to Rito for Lala's sake. Although it's possible that she could have done this out of jealousy from how close Momo was getting to Rito.

Appearance
Mikan has gold brown eyes  and  brown hair, she is described to be really cute by some characters. A ccording to a "Full size Dakimakura Cover-Mikan Version", her BWH measurements are 70-52-73.

Personality
As a younger sister, Mikan is widely known for her maturity and reliability for her age. Her maturity is also quite unique, as while she is Rito's younger sister and the youngest character in the cast, she is arguably more adult than most of the other characters, and basically acts as a big sister, wife, or mother to Rito and all who live in her house.

Because she is very good at cooking and housework, she essentially takes care of her big brother. Rather than looking up to him, she instead treats him like he is her little brother, and rarely calls him "Onii-chan", as she used to. Mikan generally treats Lala the same way, enjoying her company like a little sister and pleased to see her brother's life becoming more entertaining upon her arrival.

Mikan is very perceptive, as she is good at understanding other people and noticing their feelings. She knew very quickly her brother's crush on Haruna, and Haruna's similar feelings for Rito as well. And she knows that Rito is too scared and immature to enjoy perverted things, and that Lala is innocent and quite childish, so she doesn't mind catching Lala naked in her brother's bed in the morning, and even treats it like something normal. But she particularly doesn't like Momo sneaking into his room at night and sleeping with him, because of how sexually  mischievous  she can be towards him.

Like a big sister or mother, she would try to protect Rito from sexual temptations, and doesn't like it when girls with more perverted tendencies like Momo and Mea would do perverted things to him. She tries as often as she can to watch out whenever Momo gets the opportunity to be alone with Rito, and even guards his room at night to stop her from sneaking in and sleeping next to him. She also doesn't particularly like Mea when first meeting her, and though she tried to get to know Mea better after learning that she is Yami's sister, she finds that she cannot deal with her type and likely can't become close friends with her as she is with Yami.

Mikan seems to get along quite well with characters who are more level-headed, composed, and mature, such as Golden Darkness (Yami) and Rin Kujou. In To LOVE-Ru Darkness, despite being older than even Mikan's big brother, Rin seems to have become friends with her, and is astonished that someone like Mikan is the younger sister of someone like Rito. And Mikan is the only person whom Yami truly considers to be her friend. Rito explains that because she is so mature and reliable for her age, deep down, Mikan can get lonely without people she can relate with, and so she can use older friends who are like big sister figures to her, whom she can lean on (To LOVE-Ru Darkness chapter 5).

Trivia

 * Mikan has a case of Astraphobia, the fear of thunderstorms.
 * Like many other anime girls (and some guys), Mikan entered Saimoe Contests.
 * ​To see her result, visit here: http://saimoe.wikia.com/wiki/Yuuki_Mikan
 * To vote for her when the match is on, visit here:  http://www.internationalsaimoe.com/voting/
 * Her name Mikan is derived from the fruit Orange(Mikan is the Japanese of the fruit orange).
 * Mikan's cameo appearance with Celine in chapter 1 page 37 in the manga Mayoi Neko Overrun!



And again in chapter 3 with her friends in page 26.

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And again in chapter 6 at the final page.



In fact she makes more cameos in it than any other character in the series.